Its a pulley mounted in a frame.

You use your tree saver to attach the pulley to a tree, run the winch cable around the pulley and connect hook of winch cable back onto the frame of the bike. If you have done any physics, you will understand that this will effectivly double your winch power.

It can also be used in a similar manner to route a cable around an object like a big rock or something, but the former is the more common use of a snatchblock.

Some ****** blocks use multiple pulleys to run the cable between the bike and tree multiple times, each time multiplying the force applied by the winch.

 

I have an '03 Rincon. I have always had WARN winches on everything. Easy to gets parts, good customer service, and reliable. Thanks to the dealer I bought my Rincon from, the charged me for a regular front mount ($40) but ordered me the Multi-mount ($108)( this is the mount with a receiver in the front and back just like a towing receiver on your truck). Small disadvantage is that it does stick out a little though. I have never had a problem on the steep and nasty trails I have been on. Advantages are: you can use it in the front or the back, you can buy a insert to use front/back for pulling somebody out or being pulled out by somebody. I also have a Foreman, I bought the multi-mount and wire kit for that, so I can use the winch on either Quad. As somebody else suggested earlier, I would also buy a strap ( a must for putting around trees) and a snatchblock. This will increase your pulling power if needed, and allow you to change directions of your pull if needed. Sorry to write a book, but hopefully this will help. Good luck and have fun.

 

Definitely get a winch. I don't use mine every day, every week or maybe even every month, but when I do need it it's there. And being there when you do need it is what it's all about.