$30 Caldwell 9"-13" Bi-Pod for sling swivel stud. It is in fine condition and works perfectly. They click in at full extension (13") and have spring-assisted retraction back to 9". But they do not have 1" grooves between those two lengths. This bipod is from a rifle that was was modded into a perfect target rifle, but now I am parting it out and this is the bipod.