High Performance Racing Torque Spring clutch springs GY6 50cc-100cc 139QMB Engine Moped ATV (2000RPM,Red)Size: 2000RPMRed Color, 2000RPM, 3 pieces of Clutch Springs & 1 Torque Spring The lowest rated 1K Springs may provide a higher speed overall but engage at a lower RPM on take-off, making it challenging to "climb the hill." The 2K Springs offer the greatest grabbing power and a higher RPM at take-off, allowing for easier "hill climbing," although they may result in a slower overall speed. The 1.5K springs offer balanced performance. Please Note: The exact performance of upgrade parts will be affected by many other factors. Product dimensions: 5 x 2.52 x 2.48 inches.