Another recommendation for the OP-tech strap on Amazon. I prefer the mini for my 32L Kit bag. https://www.amazon.com/gp/product/B0001TST8U/ref=oh_aui_detailpage_o04_s00?ie=UTF8&th=1

I also own theTom Bihn Absolute Strap and use it with my Aeronaut 45. That would work also. I discovered the OP-Tech strap when looking for a slightly smaller strap, similar to the Absolute Strap, for my Tom Bihn Pilot. Great straps.