The Hang-On BuddyTM hooks adapt to virtually any treestand with single or dual backbars as seen to the right.	Single backbar treestands with up to a 1-1/2" vertical riser Dual backbar treestands with up to 1" vertical risers and up to 5" apart
Example: You have three treestand locations and own one treestand; order one Pro Pack and two Mounting Base Kits . Attach the Pro Pack hooks to your treestand and spread out three Mounting Bases in the field. Example: Some may only wish to take advantage of the safety and ease aspect of the system, in which case order a Pro Pack for each treestand you will use.
On-Line From The Sportsman's Guide