This single top strap can be added on to the top of any of backpacks. 
 
In general the single top straps are more simple to use and provide good compression in the top portion of the pack. You can often get away without using side compression straps when just using a single top strap. The Y straps are better for gear storage. 
 
Uses:
-You can run two of these straps over the top to carry a bear canister. 
-Two of them can be used on the bottom of the pack for carrying additional items. 
-They can be used as additional compression straps on the sides or front of the pack. 
 
 
Made of:
5/8" webbing
5/8" buckle
gated G hooks for easy install/removal
 
Weight- .9oz
Length- 28"