The INK-0650 is the replacement blade for the INK-0649, the pruning saw in INK's sheathed hand saw line.
It's the same 110 mm (4.3 in) blade the saw comes with, 0.5 mm thick in SK-85 carbon tool steel, for twigs, small branches and green wood. When the teeth dull, fit a new blade and keep the handle and sheath.
INK saws are made by Ishinoko Kogyo in Sanjo, Niigata, Japan. The company started in 1946 as Ishida Saw Works, was incorporated as Ishinoko Kogyo in 1969, and designs and makes hand saws, including its Genbaya line.