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A modular 3U rack mount enclosure built around 12 HD adaptor positions. Build it with ribbon pigtails and four splice trays for up to 288 LC fibers, or load OOFC splice cassettes for up to 432 LC fibers. Two or three units join on 6U or 9U stacking brackets.
Pick the connector, polish, fiber style and fiber type, and the HD3U is built and loaded to suit. Ribbon pigtails on Corning fiber cover high-count LC; loose tube pigtails cover lower counts; OOFC cassettes put the splice inside each module.

Mixed LC/UPC and SC/APC plates.

Ribbon LC build, 288F: 12 HD 24-port adaptor plates, ribbon singlemode pigtails, and black metallic splice trays.

Twelve 36-port splice cassettes take the adaptor plate positions. Splicing and slack storage are inside each cassette, for 432 LC fibers in 3U.

The chassis ships with HD adaptor plates loaded in the connector and polish you choose, with no pigtails and no splice trays. Example: HD3U-A-LC-288.

The bare chassis, with no adaptor plates, pigtails or splice trays. All 12 HD adaptor positions are open for the plates or splice cassettes you add. Order as HD3U-E.

HD9U: three HD3U units on 9U stacking brackets, front doors down.
An HD6U is two HD3U units on a pair of 6U stacking brackets; an HD9U is three HD3U units on a pair of 9U stacking brackets. Codes follow the HD3U key with the HD6U or HD9U prefix. Stacks are built with ribbon pigtails, splice cassettes, adaptors only or empty; loose tube is not offered on stacks.
| Maximum Fibers | 3U · HD3U | 6U · HD6U | 9U · HD9U |
|---|---|---|---|
| LC, ribbon pigtails + 4 splice trays per unit | 288 | 576 | 864 |
| LC, OOFC-36 splice cassettes | 432 | 864 | 1,296 |
| SC | 144 | 288 | 432 |
| Loose tube pigtails | 144 | Not offered on stacks | |
6U and 9U figures are "up to" totals: 2x and 3x the single-unit maximum. Every unit keeps its own doors, lids and sliding tray.

Rear: lids and rear panels off; each HD3U’s ribbon pigtails drop through the aligned 1.5 in pass-through knockouts into its own HD3US tray.
To keep splicing out of the patch panel, order the HD3U as an NT build (ribbon pigtails installed, no splice trays; e.g. HD3U-R-LC-288-NT, HD9U-R-LC-864-NT), or adaptors only, and splice in a companion HD3US splice-only enclosure. Each HD3U has a 1.5 in [38.1 mm] pass-through knockout at the rear, aligned through the base, sliding tray and rear lid, so ribbon pigtails drop straight down to splice remotely.
A remote-splice stack ships as one part number: HD3U panels with ribbon singlemode pigtails and no splice trays (-NT builds), stacked over HD3US splice-only enclosures, one HD3US for every six HD3U. Pigtails drop through the 1.5 in [38.1 mm] pass-through knockouts into the HD3US trays, one 288F tray per HD3U.
| Part Number | HD3U | HD3US | Trays | Rack | Fibers |
|---|---|---|---|---|---|
HD21U-R-LC-1728 | Remote splice stack, 1,728F: 6x HD3U with 288-port LC/UPC plates and ribbon singlemode pigtails, over 1x HD3US with 6 black splice trays. | 1 | 6 | 21U | 1,728 |
HD42U-R-LC-3456 | Remote splice stack, 3,456F: 12x HD3U with 288-port LC/UPC plates and ribbon singlemode pigtails, over 2x HD3US with 6 black splice trays each. | 2 | 12 | 42U | 3,456 |
HD21U-R-SC-864 | Remote splice stack, 864F: 6x HD3U with 144-port SC/UPC plates and ribbon singlemode pigtails, over 1x HD3US with 6 black splice trays. | 1 | 6 | 21U | 864 |
HD42U-R-SC-1728 | Remote splice stack, 1,728F: 12x HD3U with 144-port SC/UPC plates and ribbon singlemode pigtails, over 2x HD3US with 6 black splice trays each. | 2 | 12 | 42U | 1,728 |
HD21U = 21U: 6x HD3U over 1x HD3US. HD42U = 42U: 12x HD3U over 2x HD3US. LC = LC/UPC · LA = LC/APC · SC = SC/UPC · SA = SC/APC. APC: replace LC with LA or SC with SA in the same code, e.g. HD21U-R-LA-1728 or HD42U-R-SA-1728.

Front: HD3U doors closed; HD3US door open with one tray slid out.
View the HD3US| Rack Units | 3U, 19 in rack mount |
|---|---|
| Dimensions (H x W x D) | 5.24 x 17.70 x 16.06 in [133.0 x 449.6 x 408.0 mm] |
| Width with Rack Ears | 19.01 in [482.8 mm] |
| Weight | Approx. 23 lb [10.4 kg], empty |
| Material | 16 ga galvanneal steel, black powder coat |
| Origin | Made in USA |
| Slot Type | 12x HD adaptor positions |
| Adaptor Types | LC duplex and SC duplex adaptors, plus LC quad on patch-only or HD3US builds |
| Capacity | LC: 288F (ribbon pigtails, 4 splice trays included) or 432F (splice cassettes); SC: 144F; loose tube: 144F |
| Fiber Access | Front and rear doors, removable lids, sliding tray |
| Cable Entry | Rear, with strain relief; 1.5 in [38.1 mm] pass-through knockout |
| Stacking | 6U (2 units) and 9U (3 units) brackets |
| Pigtails | Corning fiber, 3 m overall: 18 in [457 mm] color-coded 900 µm fan-out, then ribbon |
| Standards | IEC and TIA/EIA compliant; RoHS and REACH compliant |
| In the Box | Rack bracket kit, strain relief bracket, laser warning sticker, rack screws (4), zip ties, Velcro, port ID chart |
| Compliance | Build America, Buy America (BABA) compliant, self-certified. Compliance letter available on request. |
| Documentation | Test data and certificate of conformance available on request. |

Front and side views, doors closed. Dimensions in inches [mm].
| SM LC/SC | MM LC/SC | |
|---|---|---|
| Insertion loss, max / typical | 0.20 / 0.15 dB | 0.20 / 0.15 dB |
| Return loss, UPC | 55 dB min | 30 dB min |
| Return loss, APC | 65 dB min | n/a |
| Part Number | Description | |
|---|---|---|
HD3U-L-LC-72 | Loose tube, 72 ports LC/UPC (6x 12-port LC plates), 3 m 900 µm single fusion pigtails and splice trays | Quote |
HD3U-L-LC-144 | Loose tube, 144 ports LC/UPC (12x 12-port LC plates), 3 m 900 µm single fusion pigtails and splice trays | Quote |
HD3U-L-SC-72 | Loose tube, 72 ports SC/UPC (6x 12-port SC plates), 3 m 900 µm single fusion pigtails and splice trays | Quote |
HD3U-L-SC-144 | Loose tube, 144 ports SC/UPC (12x 12-port SC plates), 3 m 900 µm single fusion pigtails and splice trays | Quote |
HD3U-R-LC-144 | 144 ports LC/UPC (12 plates x 12), ribbon singlemode pigtails, 4 splice trays included | Quote |
HD3U-R-LC-288 | 288 ports LC/UPC, ribbon singlemode pigtails, 4 splice trays included | Quote |
HD3U-R-LA-288 | 288 ports LC/APC, ribbon singlemode pigtails, 4 splice trays included | Quote |
HD3U-R-LC-288-NT | NT: 288 ports LC/UPC, ribbon pigtails installed, no splice trays; splice in a separate HD3US | Quote |
HD3U-C-LC-432 | 432 ports LC/UPC, 12x 36-port splice cassettes (configure to order) | Quote |
HD3U-C-LC-288 | 288 ports LC/UPC, 12x 24-port splice cassettes (configure to order) | Quote |
HD3U-A-LC-288 | Adaptors only: 288 ports LC/UPC on 12 HD 24-port adaptor plates; no pigtails, no splice trays | Quote |
HD3U-E | Empty chassis: no adaptor plates, pigtails or splice trays | Quote |
HD6U-R-LC-576 | 576 ports LC/UPC (24 plates x 24), ribbon pigtails, splice trays | Quote |
HD6U-R-LC-576-NT | 576 ports LC/UPC, ribbon pigtails installed, no splice trays (NT): splice in an HD3US | Quote |
HD6U-R-LC-432 | 432 ports LC/UPC (18 plates x 24), ribbon pigtails, splice trays | Quote |
HD6U-R-SA-288 | 288 ports SC/APC (24 plates x 12), ribbon pigtails, splice trays | Quote |
HD6U-A-SA-288 | Adaptors only: 288 ports SC/APC; no pigtails, no splice trays | Quote |
HD6U-C-LC-864 | 864 ports LC/UPC, 24x 36-port splice cassettes (configure to order) | Quote |
HD6U-C-LC-576 | 576 ports LC/UPC, 24x 24-port splice cassettes (configure to order) | Quote |
HD6U-E | Two empty chassis on 6U stacking brackets | Quote |
HD9U-R-LC-864 | 864 ports LC/UPC (36 plates x 24), ribbon pigtails, splice trays | Quote |
HD9U-R-LC-864-NT | 864 ports LC/UPC, ribbon pigtails installed, no splice trays (NT): splice in an HD3US | Quote |
HD9U-R-SC-432 | 432 ports SC/UPC (36 plates x 12), ribbon pigtails, splice trays | Quote |
HD9U-R-SA-432 | 432 ports SC/APC (36 plates x 12), ribbon pigtails, splice trays | Quote |
HD9U-A-SC-432 | Adaptors only: 432 ports SC/UPC; no pigtails, no splice trays | Quote |
HD9U-C-LC-1296 | 1,296 ports LC/UPC, 36x 36-port splice cassettes (configure to order) | Quote |
HD9U-C-LC-864 | 864 ports LC/UPC, 36x 24-port splice cassettes (configure to order) | Quote |
HD9U-E | Three empty chassis on 9U stacking brackets | Quote |
HD21U-R-LC-1728 | Remote splice stack, 1,728F: 6x HD3U with 288-port LC/UPC plates and ribbon singlemode pigtails, over 1x HD3US with 6 black splice trays. | Quote |
HD42U-R-LC-3456 | Remote splice stack, 3,456F: 12x HD3U with 288-port LC/UPC plates and ribbon singlemode pigtails, over 2x HD3US with 6 black splice trays each. | Quote |
HD21U-R-SC-864 | Remote splice stack, 864F: 6x HD3U with 144-port SC/UPC plates and ribbon singlemode pigtails, over 1x HD3US with 6 black splice trays. | Quote |
HD42U-R-SC-1728 | Remote splice stack, 1,728F: 12x HD3U with 144-port SC/UPC plates and ribbon singlemode pigtails, over 2x HD3US with 6 black splice trays each. | Quote |
Custom | Other connector, polish, fiber type and count combinations within capacity, configured to order | Quote |
Part number format: HD3U-[L/R/C/A]-[LC/LA/SC/SA]-[count] or HD3U-E; stacks use the HD6U or HD9U prefix. C = OOFC splice cassettes (LC/LA only). Suffix -NT (ribbon builds) = pigtails installed, no splice trays, for splicing in a separate HD3US. Fiber style: L = 900 µm loose tube pigtails, R = ribbon pigtails, C = OOFC splice cassettes (LC/LA only), A = adaptor plates only, no pigtails or trays; E = empty chassis, no suffix. Connector/polish: LC = LC/UPC, LA = LC/APC, SC = SC/UPC, SA = SC/APC. Trailing number = fiber count (port count on A builds). Singlemode is standard; multimode available on request.

24 or 36 spliced LC ports in one HD position.
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LC, SC, LC quad, MTP, Cat 6 RJ45 and blank, one footprint.
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MPC-24-LC-A (Type A) and MPC-24-LC-U (Method B / Universal): 2x MTP-12 to 12 LC duplex.
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3U, 6 sliding trays, 1,728F.
View →5-page PDF: builds, remote splicing, 6U and 9U stacks, dimensions, specifications and part numbers.
The part number from the builder is filled in for you. Sales replies by email with pricing and lead time.
+1 (702) 337-2788 · sales@oneoptics.com