When hurricane Irma came flying into South Florida I was not well prepared to protect my large windows so I put some 5/16 hanger bolts around my manufactured home windows for plywood shutters I have made. I purchased some 5/16 white thread protectors from WIDGETCO and they work okay but when I put a dab of grease to protect the bolt from rust a suction is created which makes for difficult removal of the plastic protector. So.....I refined the idea by going a size bigger to 3/8 and voila..problem solved! Excellent product and service is great!! The best part is if some of these dry up and crack they are inexpensive enough to replace :) Thank You WIDGETCO.