what is the difference between thes and the ones acos sells?
A proper bump stop.
A way to attach them to the bump tower.
A way to lock the adjusting ring into place.
A poly isolator.
The thickness of the upper ring.
JKS upper ring sits flush to the body. Doesn't look like these can without modifying the upper ring.
The thread count of the tube.
I would also guess the quality of the material, but don't know.