All of our woven felt belts are made of the finest quality wool and synthetic blends, with an approximation of 90% wool and 10% synthetic mixture, They will shrink. Some belts may be too big and you will need to saturate them and put them on your drums to dry. Sometimes they will just fit and we recommend that you dampen your belt and put it on the expand drum or sander drums until it dries. Once the belt is dry, run at least 10 to 20 seconds, and then pull them off your machine and store in an airtight container so it won`t become contaminated until your are ready to use it.