So I've purchased two different new bore up cylinders. The first is from Czech republic and I have to have imported from Pavol/Springer custom owner. The second is a new TNT cylinder set. So far the Czech republic one is definitely better quality but both are nice. I like that the tnt comes with an upper receiver made specifically for it. I believe the tnt is slightly bigger. The tnt mav set is advertised as having 43cc. Both allow lighter pull and work better with heavy ammo for barrels over 400mm. Here's some photos. The Czech republic one has custom made 14mm springs which is very cool!