Ordinary *fingering*, I'd presume? :-)

I got one a while back which is basically a 3/4"-ish curved bit of steel with a velcro strap. Fits round a finger, velcros on so it stays in place, and it's small enough to sit between two finger joints so it doesn't significantly screw up your fingering. I like smaller slides (no longer than my finger) but this was too small for me to do much with so I never really used it. I'm sure they're still selling them, but if you can't find one then PM me and I'll post you mine.

There's also some spring-loaded widget that I've seen in the Elderly catalogue. Again it attaches to your finger somehow, but this time there's a middle bit that attaches to your finger and the slide bit flicks round the side/top. When you need the slide, you pull it round with the next finger - let it go and it goes back again so you can use your finger fairly normally. This is a full-length slide, as opposed to the diddy one I've got which could only get two or maybe three strings at most. Seem to remember it was a bit pricey though.

Graham.