The top two photos are of a strap tab that was made for me by one of the guys that started me bowhunting in the early 60s. This uses a small piece of cut off nail at the end. You can see where I added another layer of leather over the end because of wear. This one is really nice to use for driving, climbing, eating, whatever as it is out of the way but is on the string in an instant.
The bottom two pictures is a very similar strap tab in how it works but this one goes around the little finger. You can see in the last photo that there are adjustment holes and that it is made of one continuous piece of leather and riveted together.
These are quick to get on the string and make for a faster arrow but with a noise gain. The first time using these is a bit scarey as you're not sure that the thumb pressure can hold it. But it really is easy to get use to.