Amazon.com: ZUKKA Revoshift 6 Speed Shimano Right Shift Lever SL-RS35-6R Bicycle Twist Shifter Lever Mountain Bike Commuter Bike Folding Bike : Sports & Outdoors
My daughter's Trek came with a 6-speed Shimano Revoshift SIS Index. It's a new bike. She can shift to higher gears easily but does not have the grip strength to shift back
Shimano Sl-rs25 Mountain Bike Revoshift Shifter Clamp Band 3x6 Speed Iamok Bicycle Parts - Bicycle Derailleur - AliExpress
Shimano RevoShift SL-RS31 3 x 6 Speed Twist Grip Brake Lever Shifter Set | Wish