Even wall thickness for maximum strength and durability Molded-in ribs for strength and abrasion resistance Reinforced ropeholds Designed for use by trailered boats and in permanent protected moorings Unique Polyform valve for years of service. Model G1 G2 G3 G4 G5 SIZE (Diameter x length) 8.9 x 32.5 cm 11.4 x 39.4 cm 14 x 48.3 cm 16.5 x 55.9 cm 22.4 x 68.1 cm EYE DIAMETER (Diameter x length) 1 cm 1.3 cm 1.6 cm 1.9 cm 1.9 cm CIRCUMFERENCE 27.9 cm 35.9 cm 43.9 cm 51.9 cm 70.2 VOLUME [liters] 1.5 L 2.6 L 5.3 L 8.3 L 19.3 L