http://www.airsoftgi.com/images/imag...9_ghopbuck.jpg
the little thing on the right is what he is referring to
also, silicone oil prevents the hopup from working like its supposed to. the hopup adds the spin to BB, how? friction. lube kills friction, therefore kills your hopup.
So dry out your hopup unit or fire ALOT of BBs through it, I agree its easier to install a hopup sleeve if its lubed, but its not good for the function