S (for forearm 17cm-23cm): length of about 36cm， small mouth circumference 16cm， 21cm circumference big mouth M (for forearm 23cm-28cm): length of about 39cm， small mouth circumference 17cm， 22cm circumference big mouth L (for forearm 28cm-33cm): length of about 42cm， small mouth circumference 18cm， 23cm circumference big mouth XL (33cm or more for the forearm): length of about 44cm， small mouth circumference 19cm， 24cm circumference big mouth
Normal Edition (without collision) Enhanced version (with bumper)
