Open Frame Rack — 2-Post and 4-Post Server Racks
Two-post and four-post open frame racks for network, telecom and staging environments.
An open frame rack is a 19-inch frame without doors or side panels, typically 6U to 42U high and rated 300 kg to 600 kg. Two-post frames suit shallow network equipment; four-post frames support servers and deeper loads. Common depths are 450 mm to 1,200 mm.
Last reviewed: 2026-11-07
Open frames are used where the room is access-controlled and airflow is managed at room level. They cost less and provide fast access.
A 2-post frame is common for telecom and patching; a 4-post frame adds front and rear support for servers.
Best for
- Telecom and patch-panel rooms
- Staging and test labs
- Projects needing low-cost open access
Key specifications
Open frame rack comparison
| Type | Support | Typical use |
|---|---|---|
| 2-post | Front mounting | Switches and patching |
| 4-post | Front and rear rails | Servers and storage |
| 4-post with castors | Mobile frame | Staging and labs |
How to choose
Choose 2 or 4 post
2-post for patching; 4-post for servers and heavy equipment.
Check stability
Bolt the frame to the floor or use a stabilizer for tall racks.
Plan airflow
Open frames rely on room airflow; keep the hot and cold paths separate.
Two-post vs four-post open frames
A two-post rack has two vertical posts and is used for switches, patch panels and shallow network equipment. It is compact and inexpensive but cannot support deep, heavy servers without additional support.
A four-post rack has front and rear posts and supports servers, storage and UPS units. It is the better choice for lab and staging environments where equipment depth and weight vary.
Height, depth and load
Open frames are available from 6U to 42U. A 42U frame has 1,866.9 mm of mounting height. Depth ranges from 450 mm for network equipment to 1,200 mm for servers. Check the depth against the longest device plus cable clearance.
Typical static load is 300 kg to 600 kg for a four-post frame; two-post frames carry less. Anchor the frame to the floor for tall configurations, and use leveling feet or castors only for positioning.
Airflow, access and security
An open frame gives unrestricted airflow and 360-degree access, which is useful in labs and staging areas. The trade-off is no dust protection, no lockable security and no controlled hot/cold aisle.
For production rooms with security or airflow requirements, add a closed cabinet. For temporary or technical areas, an open frame is often the practical choice.
Accessories and selection
Common accessories include shelves, cable managers, PDU brackets, castors, leveling feet, baying kits and blanking panels. Select the frame by U height, depth, load and access. Confirm the floor anchor and the equipment weight before ordering.
Open frame rack reference
| Type | Height | Depth | Typical load |
|---|---|---|---|
| Two-post | 6U–42U | 450–600 mm | 150–300 kg |
| Four-post | 6U–42U | 600–1,200 mm | 300–600 kg |
| Wall-mount frame | 6U–18U | 450–600 mm | 60–100 kg |
| Server frame | 22U–42U | 1,000–1,200 mm | 600–800 kg |
Open frame vs closed cabinet
| Item | Open frame | Closed cabinet |
|---|---|---|
| Cost | Lower | Higher |
| Airflow | Unrestricted | Controlled |
| Security | None | Lockable |
| Dust | No protection | Protected |
| Access | 360° | Front/rear |
| Best for | Lab / staging | Production |
Open frame selection checklist
| Item | Target | Why |
|---|---|---|
| Posts | 2 or 4 | Equipment depth |
| U height | Equipment + 20% | Growth |
| Depth | Device + 150 mm | Cables |
| Load | Weight + 25% | Safety |
| Anchor | Floor / wall | Stability |
| Accessories | Shelves / PDUs | Function |
Frequently asked questions
08 Q&A Can a 2-post rack hold servers?
Are open frames cheaper?
Do open frames need a cabinet?
What is an open frame rack used for?
What is the difference between a two-post and four-post rack?
How much weight can an open frame rack hold?
Can an open frame rack be used in a data center?
What depth does an open frame rack need?
Related pages
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