This boat cover vent will prolong the life of your boat's upholstery by helping to prevent the growth of mold, mildew and bacteria, which can occur from moist, stagnant air under your cover. The Sewable Vent Pole Cap is molded as a single component from UV-stabilized polyurethane, which protects against damaging UV rays. The flexible cap aligns with the load to prevent premature fabric wear. Use in conjunction with Support Poles (sold separately) to create proper tenting that will shed rain or snow off the top of your cover and prevent pooling.