The Chief Manufacturing PAC526 Large In-Wall Storage Box simplifies flat panel installation by providing an organized, recessed space for routing excess cables and for attaching surge protectors/power conditioners. Compatible with the PST, PRO, PLP, MSR, MTR, MWH, MWR, PWR, PNR, PDR, Thinstall, and FUSION wall mounts.
https://assetserver.net/_assets/chief/pdf/pac526-spec.pdf