Use for waterproofing RV's, trailers, boats etc Gives an excellent seal behind windows and doors Great for sealing under vents. Non-hardening with excellent sealing properties Long shelf life of a year or more. Tolerance of +- 1/32" Thickness and +- 1/16" Width 1/8" x 1/2" x 45' Gray Butyl Tape. Commonly used behind the flange on windows and doors. Excellent sealing properties. Adheres to many products including metal and glass. Non-hardening material allows it to conform and stick to the items being sealed. Long shelf life of a year of more.