This little bushing is the unsung hero of sub-slab depressurization systems. It’s made to fit a 5" cored hole and snuggle perfectly around 4" Schedule 40 pipe.
The inner lip isn’t meant to hold the pipe in place (that’s what bracing is for), but it does help it seat nicely and stay snug — no wiggling, no awkward gaps. As a bonus, it gives that pipe-meets-slab junction a clean, finished look because sometimes, it’s the little details that make your system look (and work) like a pro job.
