This is from the manufactures web page:1/2 INCH SOLE SPIKES
If you wear standard fixed sole wading boots, boot foot waders, or other footwear with a good think sole, you will want to purchase our 1/2 inch Sole Spikes for extra staying power in your footwear. Sole Spikes work great in felt or rubber soles!
3/8 INCH SOLE SPIKES
If you wear sandals, light soled shoes like sneakers, or convertible sole boots like Korkers you will want to purchase our 3/8 inch Sole Spikes.FishUSA StaffProfessional Angler