The GlowSpek Premier Safety LED Flashing Bike Pedals with Wrench (for 9/16” Axle) was designed for one primary function - SAFETY. At Glowspek, the primary goal is to provide peace of mind and safety when riding a bicycle at night. Research shows that most bicycle accidents occur during the night. The SOLUTION, the Glowspek LED Flashing Pedals. No Batteries needed! This PREMIER pedal contains 8 LED lights on each pedal. The light activates as the user spins the pedals, without any batteries needed. It provides 1,500 feet of nighttime visibility! Product Dimensions: 4" L x 3 1/8" W x 1 1/4" H. Bolt Dimensions (Fits 9/16" Axle): Crank 9/16'' for thread Weight: .45 lbs.