The Rock Slide Guitar Slides

[crank]

Would not work for me. Lots of times I wan to play 3 strings, A shape I guess. I don;t think that ring could do it and if it could youw would have to be very precise in it's placement.

I saw a guy use something like this once.

https://www.jetslide.com/product-page/jetslide-brass-bar

It is kind of a good idea, I think, because you can easily turn it around and fret normally and then spin it back for slide.

 

[wileypickett]

Similar idea, but I prefer this one:

Shubb AX Reversible Guitar Slide | eBay

When rotated behind the hand (which takes less than a second), it leaves all the fingers free for unencumbered, conventional fretting. It works so well because of the unique 2-piece design: the Delrin "ring" section remains in place on the finger as the brass "sleeve" section is rotated with the...

www.ebay.com

I was skeptical it would work as advertised, but it does.