Fitting the gaiter video:   https://youtu.be/_C91YAMBEDM 
 
Flex Boots come with protective gaiters as standard. The gaiter is made of nice soft neoprene, with laminated fabric on both sides. The neoprene gaiters follow the shape of the TPU gaiters and protect the feet from possible rubbing.
Flex neoprene gaiters are very durable when the boot is properly fitted to the hoof. Available in ten different colours, the gaiters are great for making your Flex Boots unique. And with four size options, you can further improve the boot fit by choosing smaller or larger gaiters for thick or thin legged horses.
Sold individually 
Protective soft neoprene gaiter with fabric laminated on both sides, without stitchings.
 
XS...  Flex Hoof Boot sizes 80, 85, 90, 85 and 100
SMALL... Flex Hoof Boot sizes 105, 110
MEDIUM... Flex Hoof Boot sizes 120 , 125, 130
LARGE...Flex Hoof Boot sizes 135, 140, 145 and 150
For finer or the thicker boned horses, you can also use smaller or bigger gaiters with the flex hoof boots.