As professional coaches know, compared to simply measuring heart rate, which can easily be affected by environmental factors or personal physiological conditions, using a power meter is the best way to gain metrics for training because the data given by direct force shows the real output from every pedal stroke.Key Features:IPX7 waterproof, anti-dust casing with a closed magnetic rechargeable design protects the PowerPro from water or dust while riding107mm BCD for SRAM Force and Rival 4 bolt 1x or 2x chain ringsHigh-capacity lithium battery delivers up to 150 hours of riding on a single chargeBuilt-in magnetic connector makes recharging easyGreen and red LED Indicators display connection and battery statusSpecification:Weight: 155g (spider only)Size: 125*125*200mm / 4.9*4.9*7.8 inch (L*W*H mm)Waterproof: IPX7Bolt Pattern: 4 BoltBolt Circle Diameter (BCD): 107mmChain Ring Compatibility: 1x ,2xConnections: BLE/ANT+Battery Type: Lithium-ionBattery Run Time: 100 HoursBattery Charge Time: