I have been using
Original Grip Buddies on my BMWs and Royal Enfield for the past 4 years and like them. They really help to reduce vibration and make the grips feel more comfortable. They are easy to install and seem quite durable. While you can remove them, be aware that the original sticky glue on the back of the covers is very hard to remove from the handlebars once the Buddies have been on the grips for a while.
The Royal Enfield really needs them to cut vibration through the handlebars. The Zero not so much, so I don't have them on that bike.