This is a Leupold 2 Piece Base known as the QRW, model 49841.
Leupold(R) mounts are every bit as rugged and dependable as the Leupold optics they're intended to secure. With a huge variety of mounting systems" for nearly every type of firearm under the sun" you're sure to find the perfect match for you firearm" and your style of shooting.
Features:
Matte finish
Versatile
2 Piece base
