Standard blow guns must only be used where air pressure is strictly regulated to 30 psi or less. For higher pressure air lines, safety blow guns must be specified. Safety blow guns feature a vented tip that allows air to escape if the tip is held against a solid surface, so that pressure at the tip will not exceed 30 psi, even if inlet pressure is higher. Even for safety blow guns, inlet pressure should not exceed 110 psi. All of the Greenline blow guns are supplied with 1/4" female pipe (NPT) inlets.