Fleece booties are a double layered fleece and they have elastic on the inside keeping your little ones from getting them off!!! All booties 9-12 months and larger have non slip on them called ToughTek. It is a rubber waterproof material and they are 100% machine washable! They do run small so I would suggest going up a size!
Sizes for the booties are as follows ( the inches measurements are heal to toe on the outside sole not the inside where the feet go:
3-6m 4” shoes size 2
6-9m 4.5” shoes size 3
9-12m 5” shoes size 4
12-18m 5.5” shoes size 5
Toddler booties are by shoe size and come in sizes 6(Which is an 18-24m), 7/8, and 9