X SMALL-  Length 22cm        Boot sizes 80, 90
	
SMALL -    Length 26cm        Boot sizes 90 / 100 / 110
	
MEDIUM    Length 29.5 cm    Boot sizes 120 
	
LARGE       Length 32cm        Boot sizes 130, 140 and 150
	
X LARGE    Length 35cm        Boot sizes 150
 
Flex Back strap goes around the back of the foot, over the heel bulbs, and attaches to both sides of the boot with ball rivets. Back straps are available in three sizes and four colour options, so you can make your Flex Boots unique to you. Detailed instructions for correct fitting of the back straps are in our fit & size section, and a video tutorial can be found on our YouTube channel.