HAL-RSR01 from Fry's

The switch that you've linked to is actually an SAI USR1W (seen here). Looks like Martin has a pretty good price on it, so even the price at Fry's is not really a steal.

If you are looking to buy the master switches from Fry's, you can't get them over the internet any more. If you're anywhere in Texas, you could go to either of the Houston stores, as they are rumored to have them in stock.
The answer to your question is those switches can only be used as slaves to US240s or US1130s in a 3 or 4 way circuit. When seeing these at Fry's it is easy to pick up the slaves by mistake when you really want the master switches! Good luck finding the Master switches at your Fry's. That deal will be going away soon.
OH NO, the dreaded Fry's Return......

Be sure to check for the master switches at your Fry's. That IS a good deal.

pretty sure they don't have them unfortunately. I saw the lamp and appliance ones tho, but the appliance ones didn't have the ground plug, seemed strange.
Sad thing is, I think they may be getting out of it. My Fry's here in the Chicago area has been out of the RS101 switches for quite some time. I bought quite a few there. They are now almost out of the slaves. Plenty of lamp and appliance modules, although a lot less than when they started.

Too bad, I could use some more.