I've placed this here because it really comes under "strength" training of the fingers.
I decided to get me a pair of these Eagle Loops
after seeing them in use in vids and such; the verdict, they are great. They make setting up for a middle-finger deadlift a lot easier, just loop it through and I'm away...no fiddling about with rigging that has to be made of something suitable that will hold the weightload and not cut off circulation, or worse still, cut into the finger.
I've seen youtube vids where people have used them for 150kg (two-handed) finger deadlifts, so they can take a substantial load...they are also extremely well made and are solid just to look at which gives confidence that they will not give during an attempt. They also permit a person to choose how many fingers to use on each hand, with 4 loops on each one, for the fingers (not the thumb) though I'd imagine if you chose to do a thumb lift, all you'd do is use one of the loops.