Shopper What material is this made of and what is the diameter?
SCOTT W It's nylon and it's about 4 inches in diameter.
KEVIN M The tube is made of nylon or a nylon-like material and measures 3" (7.6 cm) in diameter when inflated.
MIKE L My signal tube is about 3.5 to 4 inches in diameter and is made of nylon. Luckily, I have never had to use it and would not go in the water without it.