The nibblets holders are nothing more than PVC couplings that I tape to my HiTeks with electrical tape.I'm going to say they are for schedule 40 pvc and the text on the fitting says 1 1/2 Genova PVC 70115. Also in the pic are my HiTek adjusters, a 1/2" socket welded to a piece of flat stock with a piece of bungee cord attached. I keep 2-3 of them all around the boat. Works for me. I'm not about fancy, I'm about functional.

http://www.doitbest.com/PVC+coupling...sku-442505.dib