Punch-Lok Hose Fittings Hex Steel Lok-Nipple Single Groove 1/2" x 3/8" HX-431 144S. You get 4 each of these you see in the picture. Punch-Lok single and double groove hose fittings of all types are designed and engineered for use with Punch-Lok clamps to make connections which will withstand high pressure services. The shape of the grooves eliminates damage to the inner wall of the hose. The Punch-Lok clamp brings the hose wall into the grooves with even compression around the fittings. Part Name HX-431 Hose Size 1/2" Std. Pipe Thread 3/8" Length 2 1/2" No. of Grooves 1 Maximum Pressure 250 PSI