I used these on my GTV250 for years. They work great. They increase the handgrip diameter by about 3/16" inch so your hand isn't quite as small around the grip and reduces vibration a bit. This reduced numbness in my hands considerably.
I purchased these to replace the grip puppies on my GTV but I no longer own it. They seem to last about 5000 miles on my bike.
These are $19 on Amazon.