This is the Side Mounted Bipod/Rail kit, which is specifically designed for Breakbarrel and Underlever air rifles in that it still allows the cocking mechanism to move freely.  This can be used on both synthetic and wood stocks.  The kit comes complete with the Bi-directional folding Bipods, 5-Slot alloy picatinny rails and the four installation screws.

Made of high quality aluminum alloy material, non-rust black anodized finish, sturdy and durable.
Can increase shooting accuracy due to the excellent stability offered by bipod.
Adjustable leg design, 5 settings for different lengths to meet your different needs.
It can be folded up for easily moving your rifle by pressing down the spring tension knob.
Quick attach and detach design, suitable for 20mm rail.

Specifications:
Item Type: Bipod
Material: Aluminum Alloy
Color: Black
Leg Length: Approx. 230-305mm / 9-12inch
Center Height: Approx. 205-265mm / 6.15-7.95inch
Weight: Approx. 378g / 13.3oz

Package List:
2pc x Monopod
2pc x Picatinny Rails