I think what Saint was trying to say here is that since TM are the first to manufacture teh AEG Box the later company is simply piggy backing on their design and in time enhanced it with their own. All TM mechbox design have their flaws which were first copied by companies such as Systema, Classic army, G&P, KA, and many others.
Being one of the many pioneer of modern airsoft TM design was cloned by many companies with their version of success and failures, I remember the first batch of Zeke, Systema metal bodies they were horrible eventually after the second and third run they were one of teh best. The same can be said about Classic army and G&P the only difference between CA, KA and G&P are the KA and G&P put a bit more R&D enhancement in their product improving the initial TM flaws.
There are other aftermarket companies that buy the rights from TM to develop parts for TM companies such as Systema, Pro Gear(no longer exist), King Arms, G&P and First Factory so along the way these companies have sprouted a different batch of smaller specialized manufacturer creating customized pieces for TM based AEG/GBB so if you want to look at the bigger picture the guys are indeed copying TM design and benefiting from TM R&D.
FYI TM has many more hop up unit design other than the ones in existence on their current models, some of them are quite similar to the other manufacturer design, the only difference is that these design never made it to production.
So Hata hopefully this little history tidbits answer your question, but if it doesn't then take the King Arms, G&P and Classic army (in that same order)
Last edited by wildcard; August 16th, 2009 at 11:39..