$265, to be available on April 30, 2008
Even though this is a real steel part, there is a chance that it can be installed on a PTW, provided that the buffer tube threads are identical on the lower receiver so it may accept the magpul's proprietary buffer tube. I do see an area in the rear of the buffer tube where a screw is located, alluding to a possibility that removing this might allow for a battery power cord to run through this part, but that's just speculation for now.
You can see the screw in the rear of the buffer tube in this pic:

Unfortunately, Magpul's page warns that this part cannot be exported outside of the US without the proper export permit.
Page source:
http://www.magpul.com/catalog/index.php?ma...products_id=187



























