A small is for: Waist size ; <>28-32" [70-90cm] & or Chest size <> 34-38"[85-95cm.]As there is a lot of adjustment, these sizes may expand or subtract slightly. If you happen to weigh approx. 220lb. or more, an extra large cut may be available upon special request. [This is not a standard size]
A medium is for: Waist size; <> 32-36"[80-90cm.] & or Chest size <>38-42" [95-105cm.]
A large is for: Waist size; <>36-40" [90-100cm.] & or Chest size <> 42-46" [105-115cm.]
Head armor is a little more difficult to size due to many different facial features. However the following guide will help you. Take a cloth measuring tape, and measure around your head the same way as a sweatband or hat goes. Then measure around your head in the opposite direction from under the bottom of your chin around the top of your head as if you had a tie on bonnet. Check your measurements with those listed below. Again, there is a lot of adjustment in the helmet, so sizes can expand or subtract slightly.
Horizontal measurement is like a hat or sweatband. Vertical measurement goes up around like a bonnet.[As explained above]
Small Headpiece; Horizontal Measurement <> under 20.5" & Vertical measurement <> under 23"
Medium Headpiece; Horizontal measurement <> 20.5-23" & Vertical measurement <>23-26"
Large Headpiece; Horizontal measurement <> over 23" & Vertical measurement <> over 26"