The betas for Valve's Steam Machines and Steam Controllers are getting shipped to their testers on Friday.

This includes a select sample of 300 randomly selected Steam users. Unfortunately, all of these participants are in the US due to "regulatory hurdles."

"This was not our original plan, and it means we can't collect beta feedback from Steam customers world-wide, which is pretty unfortunate," Valve lamented in its announcement. "All things considered, we're sure it was the right decision, because the alternative was to delay the whole beta beyond the point when we'd be able to incorporate any feedback into the 2014 products."

Valve further noted that this domestic limitation would only be applicable to the prototype models and the final Steam Machines won't be affected by this.

The SteamOS will be available when the Steam Machine prototypes ship. "It will be downloadable by individual users and commercial OEMs," Valve noted. "But unless you're an intrepid Linux hacker already, we're going to recommend that you wait until later in 2014 to try it out."

Those testing the Steam Machine prototypes will receive a special badge on their Steam Community profile and some games running natively on Steam OS will be added to their library. At least one of these is Metro: Last Light.