The classic monkeysee harness is so comfy to wear and a cinch to get on and off.
For girls + guys each harness offer two stripes of high intensity reflective film for after dark visibility.
For the guys they run true to size
For the girls
S is up to size 10
M is 12 - 14
L is 16+
Comes with an adjustable slide for a generous give in the size range. If at the upper end of a size and you plan to wear a bulky jacket, might be worth thinking about going up a size.