Kuryakyn mechanical cruise assist. Parts Unlimited Street 2015 в г. Билибино

Looks like a bar end weight
Spring-loaded tensioner inside holds the throttle in position once you set it with your little finger
Easy throttle shut-down – just roll the throttle forward to disengage
Optional matching clutch bar end weight available separately
For use with OEM or Kuryakyn ISO®, Flame or Transformer grips

Note: Proper installation may require cutting a 5/8" hole in the end of your OEM grip. Handlebars must have open ends.