All Quick Disconnect (QD) fittings automatically lock in place. To connect, simply push the air hose onto the fitting. To disconnect, push back on the fitting’s plastic ring and then easily pull the air hose off. The 1/4" or 1/8" Male Fittings fit most sandblasters, wax injectors, sprue cutters, etc. You may find the 1/4" are the right size for vacuum pumps.