you have to make sure its the right length and all for your bike and it will fit like some bikes wont fit a resiviour and some can u cant just go buy a shock and try put it on ,
well to be honest here my brothers got one quiet like it and it was a genuine one and hes a big bloke giving it a thrashing and blew the seals and shit and pritty much destroyed it...
also that one would be a rip off copy so it most probably would be worse so if you know your going to give it a flogging then id look elsewheres =)
I have to agree with darb110 ..... a relo bought one thinking they'd be better than the non reservoir model and he's not too impressed with how it feels ....... to install them you HAVE to cut the seat to clear the reservoir which MUST go to the top (they're designed to work that way) ....... if you turn them upside down you'll blow the crapper out of he seals and probably seize and snap the shaft in next to no time at all ..... he also had to drill the alloy eye bushes out from 8 mm to 10 mm .... he previously had a BS-22-AR non reservoir Fast Ace shock but left it on his first bike when he sold it and says that it was a far better feeling shock ...... he weighs 105 KG BTW ......
I instinctively bought a BS 22 AR purely because I didn't like the look of the dicky looking reservior on those shocks ..... they look like they'd snap off easily .....