what are the two attachment points on the...
what are the two attachment points on the top of the hood/lumbar pack for? .... two buckle points
When you used the top pack as a lumbar pack, I believe there are two straps to thread through those buckles to stabilize the load.
Dave is correct. The same straps the cinch to the main back, are then used (if desired) and threaded through the top ladder locks for cinching down layers or what have you.