I've got an old bow saw which I use for tree pruning which must be 30 years old and still on the original rusty old blade. It actually cuts pretty well on smaller branches but it's a bit of a pain on anything over 6 inches diameter and it pulls to one side so hard you end up going from vertical to horizontal and extending the cut length by a factor of three.
It's got two adjustment / locating holes at each end. Total overal length of the whole metal piece is just under 24 inches but from hole to hole it's between 1 and 2 inches shorter depending on which holes you pick. So is that a 24" blade or not? I need to find out to order a new one.
On that topic what's a good make of blade to buy for green logs full of sap? This one grinds to a halt on fresh Leylandii and I've got a bunch of those to cut down.