4" Vent - Typically used on USP 8 Cox FootStop & Stern Sectional 4's.
5" Vent - Standard used in all Super Predator HUDSON's, USP Singles, Pair/Doubles & Fours. Now with improved seal & 1/4 turn lock.
6" Vent - USP 8's
You are in Canada, and we have a Canadian website here.