This is a Harris Engineering Fixed known as the Bipod, model 1A225C.
Harris Engineering's Ultra-Light Three Piece 13.5"-27" Sling Swivel Mount Fixed Bipod is manufactured with heat treated steel and hard alloys. It clamps to the Q.D. stud of most bolt action rifles that have a conventional stock design. Carrying your rifle with a sling or shooting off-hand is not impeded by the use of a Harris Bipod. Folding legs have completely adjustable spring-return extensions.
Features:
Legs Extend from 13.5 to 27
Three Piece Standard Legs
Hard Rubber Leg Caps
Aluminum Bipod with Steel Parts
Attaches to a Sling Swivel Stud
