Especially climbers grip, you know, when they hang by only their fingers, or even just 2/3rds of their fingers.

I've completely ignored this, but I was given advice about training up to the L-Seats by doing hanging leg raises. Well, I have a doorway which only allows me to only use 2/3rds of my fingers and I can only hang their for about 7 seconds tops. The hanging leg raises are going to have to wait a while.

Does anyone know how to improve grip strength? I'm not too sure what type grip this is either? Trust me, any advice is helpful!