Hungdao Bowling Ball Workout Tool Bowling Accessories with 3/4 and 3/5 Double Choice Replacement Blade for Thumb Fingers

I use this to fine tune my thumb holes for a great fit! It's nice and sharp, plus easy to use!

After buying a ball and having it drilled the thumb hole was just a little bit too small and I knew that taking it to the shop the guy would take off too much using a Dremel or something like that so I got this and I am telling you what, it's the best bowling accessory I've ever bought. Also you may feel ridges very slightly after using this and I mean very slightly you may be tempted to use a fine sandpaper to smooth it out but I would suggest you try without doing that. I didn't use any sandpaper to smooth out after using this tool if anything it made the tool made it more smooth. You want your groves going straight up out of the ball except for the area the inner part of the thumb touches, which comes out at an angle so put your thumb in there and notate where the thumb comes out from, the angle of direction is what mean... and use the tool at an angle that matches the inner part of your thumb as it comes out of the ball. Eazy peazy. And don't worry about taking too much out you can do a few scrapes and test it out when you get it right you'll know

As a bowler I was glad to find this. was able to make my thumb hole fit perfect, no more bowlers thumb

Works exactly like it should

If you have thumb swelling issues you need this in your bag. It's a great value for the money. It functions well and is easy to use

When it arrived I was skeptical. It didn’t look like it would do much but I was totally surprised. It works great. It cuts right through the thumb insert like butter. I keep it in my bowling bag in case I need it.

Great for adjusting your thumb hole.

Perfect!!