bucking compatability?

for a tanaka m700 hopup: http://www.airsoftpost.com/product_info.php?products_id=33373
bucking A: http://www.airsoftgi.com/product_info.php?products_id=6433
bucking B: http://www.airsoftpost.com/product_info.php?cPath=24_71_368&products_id=26183

which is better? or which works at all?

Thats a great question; sorry i can't provide a better answer, but if i were you... Id just buy both. Theyre fairly cheap.

"A" is way different than B, seeing that it comes with 3 parts instead of one and they are shaped differently o.O

I think B is specifically for the KJW M700. I'd get A because it says "for Tanaka M700". Play it safe.

This is true, I thought they both said Tanaka
If only Option A does, I'd definately go wih that.