The G-3 Series (5 1/2" diameter x19" length) is a great fender for your 15' to 20' lake boat.Polyform's G Series fender was first produced back in the mid 1980s and has become Polyform's most popular utility fender. Designed for use by trailered boats and in permanent protected moorings. Molded-in ribs for puncture and abrasion resistance. Reinforced ropeholds and even wall thickness for maximum strength and durability. For boats up to 20'.Key FeaturesEven wall thickness for maximum strength and durabilityMolded-in ribs for strength and abrasion resistanceReinforced ropeholdsDesigned for use by trailered boats and in permanent protected mooringsUnique Polyform valve for years of serviceG-Series Fender Size Selection ChartBoat LengthPolyform Fender Sizes (Diameter x Length)Up to 10'G-1: 3 1/2" x 12 13/16"10' to 20'G-2: 4 1/2" x 15 1/2" or G-3: 5 1/2" x 19"20' to 30'G-4: 6 1/2" x 22" or G-5: 8 13/16" x 26 13/16"30' to 40'G-6: 11" x 30"