It's in one of his training vids from early years. It's like a little grey bag on some rope which he ducks away from?

Whats it called? can you make it at home?

It's a slip bag (also called maize bag or something)

You can make it by filling up a balloon with rice. Then cover the balloon up with a sock, and hang it up somewhere on a light chain or just a cord.

wo kool is it effective to use?

cheers

for others it's what he's using in this vid at the start

http://www.youtube.com/watch?v=w4dWrav5yYo&feature=related

so whats it's main purpose?

cheers

for others it's what he's using in this vid at the start

http://www.youtube.com/watch?v=w4dWrav5yYo&feature=related

so whats it's main purpose?
Training head movement while punching I guess.
I think it's only useful if you're a small guy for your weight though like Tyson. But I also think the slip bag is VERY useful when you're trying to master the peekaboo style.