here is a link to one on ebay. most good bicycle shops will have this one. do not buy a cheap schinn or kmart one. go with park. they are the best tools out thier. and no i do not own stock in park or anything else i just have a lot of their tools
I bought a summit big boy chain break on ebay. After I modified it the thing works better than the park... My park was pretty tough except the pin pusher brads on me every time I use it. The steel is too soft or I wind it down way to tight.
The summit hasn't done that yet but all the chain guides broke off so I ground them down to nothing. Now I just line the chain rivet and the plunger up by sight and it works great. I always start the replacement of the rivet with a pair of pliers then use the plunger to press it home. Works every time.