Inward bars...
yes there are differences between
the first gen, second gen and third gen inward bars
to get this all straight
First gens were originally sold on eBay only, they look like SZ nipple bars, they were constructed of mild steel and MIG welded by (JP himself i believe) they are good but heavy.
SZ basically told him not to copy them so he stopped production
Second gens, were the first bars to use an internal reinforcement but they were still mild steel and MIG welded, a few were TIG welded. so they are heavier but very strong unless you got beyond 20 high the slit eventually cracks to the side and they break off, but it takes a while.
Third gens, are the newest still carrying over the internal reinforcement and the clean one piece look, but all of them are TIG welded and use 4130 chromoly tubing. so they are lighter by a bit and are stronger than the previous mild steel ones
also note a few aluminum bars have been tested but none have been successful so far