Unless you want to carry the full weight of your rifle all day you need a sling to give your arms a rest and distribute the weight across your shoulders (did we mention we stock those too?) and this is how we like to attach the sling to our rifle. One part goes on the top rail and one part goes on the end of your sling. Clip in and go! Sionce not everyone likes the position of the fixed QD points on their rifles this QD point allows adjustment to your most comfortable balance point on the top rail. Supplied with the allen key for fitting. Available in Black or Tan.