Now, you can get an official one from RedWolf Airsoft... "The Magpul PTS UBR (Utility / Battle Rifle), U.S. Patent 6651371, is a fully-featured, adjustable butt stock for AEG M4 / M16. Unlike typical collapsing stocks, this modular design offers the stability of a fixed stock with consistent cheek weld in any position. Seven-position length-of-pull (LOP) adjustment is quickly executed with gross motor movement while the integral preset system allows direct access to a preferred position.

The UBR also provides extra counterbalance weight to improve handling on full-length rifles and weapons with muzzle-heavy accessories or grenade launchers. Optional components such as dual-side sling mounts and metal strike plate allow the UBR? to adapt to the mission at hand.

Features:

• New design Receiver Extension tube which fits Lipo Battery.
• It fit short type AEG receiver only.
• 7-Position LOP adjustability with customizable preset system for fast access to preferred length.
• Made by DuPont Polymer with Reinforced Stock Body (Steel plate).
• Solid "fixed stock" lockup in all positions.
• Repositionable cheek piece accommodates users requiring extra eye-relief.
• Stout construction provides counterbalance weight for improved weapon balance and handling.
• Sling Mounts.
• Front / Rear - push-button QD sling mounts.
• Bottom - 1.25 inch Sling loop.
• Included Accessories:
• Storage Module (Left-Right Reversible / Removable).
• Rubber Butt-Pad, 0.30" (Removable).
• Front / Rear - dual side push-button QD sling mounts."