The HF4100 has a 'needle point' enclosed in the head that pushes the ball of the grease nipple down when connected, reducing the grease pressure required to transfer grease into the nipple. This eliminates the need for high clamping pressures necessitating the use of gripping jaws on standard hydraulic connectors and allows a narrower head design that facilitates access to tight spaces such as nipples on CV joints. 1/8" BSP connection thread.