Made in the USA, the Magpul STR (Storage/Type Restricted) is a drop-in replacement buttstock for AR15/M4 carbines using mil-spec sized receiver extension tubes. A storage-capable version of the CTR, the STR has improved cheek weld and two water resistant battery tubes on a compact, reinforced polymer A-frame design.
Specifications:

Type
Firearm Type	AR-15
Firearm Model
Material	Reinforced Polymer
Finish	Black
Features	Water Resistant Battery Storage Tubes
Adjustment Type	Collapsible
Positions	6
Length of Pull
Rails
Texture Type
Swivel Studs
Free Floating
Grip Type
Tube Included	No
Max Capacity