Standard Model. High quality aircraft aluminum stem, precisely machined to 1/4" NPT. Oil reservoir is fabricated of high impact plastic. Technician always sees oil supply and oiling action. Holds three to four days supply of oil. With each use of the air tool, a fine mist of precisely metered oil enters the air stream. All internal moving parts are coated and lubricated. Use on all 3/8" and 1/2" air impact guns, air wrenches, body shop air tools and pneumatic hammers. 1/4" NPT Female inlet x 1/4" NPT Male outlet.