FINIS Trainer Monofin: Series 1 Free Shipping Does Not ApplyFINIS Trainer Monofin: Series 1The Trainer I Monofin is made with a long, flexible fiberglass blade that is designed for more serious swimmers and triathletes. The Trainer I Monofin improves body balance, strengthens the core muscles and is a vital drill tool. Monofins are great strength training tools to develop a smooth and powerful butterfly kick that is generated from the hips, not the knees. Monofins work the abs, lower back, quads and gluteus, while improving flexibility of the feet and ankles.Strong KickDevelop a powerful dolphin kick that is generated from the hipsStrength TrainingWork core muscles including abs, lower back, quads and gluteusFlexibilityIncrease range of motion in the feet and anklesMade for Advanced SwimmersDesigned for more experienced swimmers and triathletesLong Fiberglass BladeAids in lengthening stroke and improves body balance