There are different sizes. Standard hiking and mountaineering gaiters come in both men’s and women’s sizes. These are then separated into small, medium, large, and extra-large. Before you buy a pair, it’s important to check with the manufacturer’s sizing chart. Grab a tape measure when fitting. And remember, if you are purchasing full length/knee high gaiters, they need to fit over the calf. In addition, you should account for the larger diameter if you plan to use them with pac boots. These heavily insulted boots are larger than a typical hiking shoe.