STEP 1: Screw the brass end onto your valve stem.
STEP 2: Slide the portion of the deflator with hose towards the stem.
STEP 3: Use the small knurled handle to grab the valve core (spin it while gently pushing toward the stem and you'll know when you engage the valve core).
STEP 4: Then rotate counterclockwise to unscrew stem. You'll get an air pressure reading on the gauge.
STEP 5: Then you can slide the hose part of the deflator away from the stem to vent air.
***Note that the pressure is not checked while you're deflating, so you have to release the pressure reading with the button on the deflator and then slide the hose portion back towards the valve stem. Do this repeatedly until you get an idea of how long it takes to get to the pressure you're looking for in the tire.***
STEP 6: Once you're there, slide the hose towards the valve stem and then push the valve core holder in towards the stem
STEP 7: Rotate clockwise (righty-tighty).
Don't over-tighten or you'll wear out the seals on your valve core faster. Only 1/4 turn needed till snug