High voltage insulation sleeve, made in the USA, it has an O.D. of 3/4 inch. It's made of red silicon and I'm not sure of the voltage rating - this was originally bought by the Lockheed Missiles & Space Co. so the numbers are military procurement numbers which only a few people know how to decode. I am selling this per ONE FOOT increments, so if you want a 1-foot piece, order quantity 1; if you want 10 feet, order quantity 10 and so on. This is new old stock.