The "B Special" Cam Lock is a new product design specifically for us homebrewers. It's a standard big bore B fitting with the threads machined off, Stainless steel and a barb for retaining the hose. This is ideal for the inlet on a Chugger Pump to maximize flow. The photo shows just how big the difference is. In terms of hole area its 50 sq.mm for the "C" vs 153 sq.mm. for the "B Special". It's compatible with types A,E and F.