Big Rock Knob Puller Tool

So this is supposed to help to remove knobs

Managed to make it work on my guitar but it was completely useless for my bass, which has similar knobs. It's very, very difficult to make it work because the inner "blades" are suprisingly thick and short. Depending on the knob, it makes it too difficult to make it fit and effectively pull. The ring seems useless, as I never quite got a way to make it fit to "lock" the knob puller. it's either not big enough (to lock it on the base) or not quite effective on its own.
Disappointed, it seemed to work well but it really depends on what type and size of knobs you have. I wish the built was also sturtier.

pros:
- it's better than nothing. I can't seem to find anything like this...
- It can work well
Cons:
- It doesn't work well that much

It's a shame because it's a good concept and I feel it could potentially be pretty good but it's just missing a bit of a better build/design

I was quite disappointed with this.
The entire tool is made of a hard plastic not a soft material to protect your precious guitar as you might expect.
Furthermore it is made of two parts split down the middle. I had to take a sharp knife and cut away flash at the bottom edge and inside of the tool and sand the bottom to a smooth finish.
Furthermore it doesnt fit dome the dome size knobs, mainly the Fender type ones.
I guess if you are willing to go to this trouble and regularly have to exchange Fender size knobs then it will be fine, otherwise I would look for an alternative.