Euroides, there are a lot of people on here who know the ins and outs of a bench shirt a lot better than me, but since nobody responded, I will try to clear it up.
Basically, a good bench shirt that a lifter has mastered how to use can add 50, 60, 70, for some guys even 100lbs to their bench press, but 50 is more like it in most cases. Some guys don't get jack shit out of a bench shirt. The idea from what iunderstand is that they help you if your weakness is off the chest, by giving you a spring of sorts to the final phase of the lift, the lockout, at which point if you have strong triceps all you need to do is lock the weight out. If you're strong off the chest and have weak tris, a shirt will not help you as much as others, if you're weak off the chest and have weak tri's, you should probably take up another sport. That basically sums it up in a nutshell, if anybody with more knowledge or experience wants to add to what I said or disagree, feel free, I just saw there were no responses, and I wanted to say a little something.
My diatribe before can be summed up like this. A good cycle of AAS will add 60lbs to your bench, on average a shirt for a master of bench shirts will add 70lbs, thats 130lbs, so 820 minus 130 is 690 without drugs and a shirt. So, the guys with 350 bench presses crying and making stupid little comments that it must be what he is "using" are jackasses because with a shirt and all the gear in the world, tey still would be nowhere 500, let alone 821. Gear and shirts help level the plaing field, they don't make the average lifter something special.
You're new to the boards, but I don't know if you're new to training or AAS or equipment, so I hope that cleared it up. It pisses me off when people don't give strength athletes the respect they deserve and feel everything is equipment and drugs. Look at baseball, does anybody out there in their right mind think that if they took Barry Bonds' cycle that they could play a MLB season and hit 73 home runs, strength sports are as much a gift and a skill as other sports.
I know I will never bench 821 no matter what, so I am not gonna say something smart-assed, I have respect. To the guys who said shit or joked about shit......Take Mendolson's AAS cycle, use his equipment, and have some spotters put 821 into your hands.....know what would happen, you'd need a brillo pad to get you off the bench.