Pro Spot is basically marketed at the home gym crowd because it has the feature of "self spotting". Which actually is nothing more than locking the weight as soon as you take your hands off the bar.
It isn't a smith machine style piece, but rather the bar is attached to cables, so you can use it for all kinds of things like curls and such that you can't do with a smith machine's fixed path of movement.
The details are :
Grab & GoŽ Operation
Olympic touch sensor barbell with spring clips
Dual-weight barbell loading system
200-lb selectorized weight stack
Barbell Holder secures barbell when performing chin ups
Hooks for securing lat bar
Side-to-side barbell ratcheting
Vinyl-coated, aircraft-grade cables, each rated for 2,000 pounds
There is a short video and some pics on this site :http://www.homegymreview.net/review/prospot-fusion-hg6/
But that is for the fancy system with tvs and such. The HG1 is a basic system that doesn't have tvs and other attachments like cable cross overs.