Hey all,
I just bought some couplings for 1 1/2 inch DWV PVC pipe, one with a ridge in the middle and one without.
They are both made my the same company, they both have manufacturing marks on one end, they both have what I believe is an ejection pin mark. The overall dimensions seem to be the same.
The one with the central ridge cost $0.65 and the one that is smooth on the inside cost $1.79
I checked a few big box stores and their pricing was similar

Does anyone have any idea why there is a nearly 3 fold difference in price?

My first guess is that there is a difference in manufacturing technique, but I know next to nothing about molding.

Any ideas?

Thanks