Have you noticed how airlines are cracking down on oversized (and in some countries) overweight carry-on bags & backpacks?  In Australia, you can only carry on bags up to 7 kgs.  Birders will usually be pushing these limits with camera gear, lenses, binoculars and guidebooks.  If you don’t want a nasty surprise when you check in and be forced to check your bag – and pay extra for it – you need to know the weight before you go.  This cute gadget also has a measuring tape built in!

You can also hide some extra weight in a Scottevest but they still don’t have a product that holds DSLRs and zoom lenses!