What it is
The Zurn Wilkins 975XL2 is a lead-free bronze wye-pattern reduced pressure assembly in ¼" through 2", with 45-degree check modules, four test cocks, ball-valve shutoffs, and a relief valve that hangs below the body at the wye junction. It is the small RP on a great deal of irrigation, backflow-tester, and commercial work west of the Mississippi and in Wilkins-spec cities everywhere else.
In 2025 Zurn introduced the 975XL3 as the upgrade path. Same job, shorter body: a ¾" drops from 12" to 10" end to end and the relief valve rises about 1½" closer to the pipe.
What matters for the cover
Wye body depth. The relief valve sits 5" below centerline on ¾" and 1", 6¾" on 1¼" through 2". The relief valve under the body has to drain. Set the cover so the base closes to the pad around the assembly but never seals under the relief port.
Pattern to the XL2. Because the XL3 is smaller in every dimension, a cover cut for the XL2 fits both generations. The reverse is not true. Until the XL3 is the majority of what your testers see, stock the XL2 pattern.
Length. 12" at ¾" and 13" at 1", so the 20 × 20 and 24 × 24 closed-top covers fit; 17" to 18½" at 1¼" through 2", where the 30 × 24 is the closest fit of the price-list group and the 36 × 24 gives room for union or OS&Y builds.
UL/OS&Y versions add gate stems and height. Send a photo.
Stocking
In Wilkins territory the 975XL2 is the highest-volume small RP cover after the PVBs. Backflow testers carry the ¾" and 1" as truck stock; irrigation supply branches stock cases of the 20 × 20 and 24 × 24. Pair with the 950XLT2 double check, which many of the same accounts install where a DC is allowed.