Rail kits are one of the most-returned server parts, because it's easy to order the wrong one. Dell PowerEdge servers use the ReadyRails system, and choosing correctly comes down to three things: your server model and generation, whether you need sliding or static rails, and your rack type. This guide walks through each so you order the right kit the first time.
Step 1 — Sliding vs static: which do you need?
Dell offers two rail families, and they are not interchangeable in capability.
Sliding rails (ReadyRails II) let you pull the server fully out of the rack for in-rack servicing, and they support a Cable Management Arm (CMA). They install tool-lessly in 4-post racks with square or unthreaded round holes. If you service servers in place or run dense cabling, choose sliding.
Static rails (ReadyRails) fix the server in position — no sliding out, and no CMA support. In exchange, they support a wider variety of racks, including 2-post and threaded-hole racks. They're lighter, cheaper, and fine for servers you rarely pull.
Rule of thumb: need to slide it out or run a CMA, choose sliding (ReadyRails II); 2-post or threaded rack or a tight budget, choose static.
Step 2 — Match the rail type code to your server
Dell groups servers into rail families identified by a type code (A7, A8, B6, and others). The kit must match your server's family and form factor (1U vs 2U):
- A7 — 1U sliding ReadyRails II (e.g. R620 / R630 / R640 and related 1U platforms)
- A8 — 1U static ReadyRails (same 1U platforms, static version)
- B6 — 2U sliding ReadyRails II (e.g. R720 / R730 / R740 and related 2U platforms)
These codes are printed on Dell rail kits. A kit for a 1U R640 will not fit a 2U R740, even though both are PowerEdge.
Step 3 — Confirm rack compatibility
Before ordering, check three rack attributes: posts (4-post vs 2-post — sliding needs 4-post; static covers both), hole type (square, unthreaded round, or threaded — sliding ReadyRails II need adapter brackets for threaded-hole racks), and mounting depth (verify your rack depth against Dell's Rail Sizing and Rack Compatibility Matrix).
Step 4 — Find the exact part number
The fastest path is the label on your existing rails, or the type code (A7/A8/B6) plus your server model. A single 1U sliding kit may appear under several Dell part numbers. If you only know the server model, that's enough for us to match the correct kit.
Quick reference
| You have | You want | Likely kit |
|---|---|---|
| 1U server (R6x0), 4-post rack, want CMA / slide-out | Sliding | ReadyRails II, type A7 |
| 1U server (R6x0), 2-post or threaded rack | Static | ReadyRails, type A8 |
| 2U server (R7x0), 4-post rack, want CMA / slide-out | Sliding | ReadyRails II, type B6 |
| Any server, tight budget, no in-rack service | Static | ReadyRails static |
Need the right rail kit?
We stock genuine Dell PowerEdge ReadyRails kits — sliding and static, 1U and 2U — and ship them free worldwide on DDP terms, all duties and taxes included. Not sure which type code fits your server or rack? Send us your server model (and whether your rack is 2-post or 4-post and square or threaded) and we'll confirm the exact kit. Browse server rack rails.
Type codes and compatibility are a buyer's reference; always confirm against Dell's Rail Sizing and Rack Compatibility Matrix for your exact server generation and rack.