Sensky MZJ507 6" - 9" Adjustable Height Spring Bipod for Hunting Shooting Rifle Air Gun High-tech durable aluminum construction and steel top platform Easy sling attachment. Fully adjustable legs with Posi-lock wheel and quick retraction button Extendable Legs: Length of both legs can be adjusted for best position Posi-lock: Unique safety design to guarantee that the position of the folding arm is fully locked