Ratchet—Ratchet-Mechanism guns only apply pressure to the cartridge while you pull the trigger. They’re good for use with thin materials that require flow control.

Thrust Ratio—To choose a thrust ratio, consider the thickness of the material—thinner materials such as silicone and latex flow easily, so choose a low thrust ratio gun. Thick materials such as urethanes and epoxies require more power to dispense, so choose a high thrust ratio.