The No. 18201 is the coarse replacement blade for the Z-Saw Tuck-In 210, the compact folding saw. The Coarse version is the orchard and vineyard pruner.
It's the same 210 mm (8.3 in) blade the Coarse saw comes with, 0.7 mm thick. The blade is held by a coin screw, so a coin is all you need to change it, and you keep the handle.
Z-Saw's maker, Okada Hardware, has made saws in Miki, Japan since 1943 and was the first company in Japan to impulse-harden saw teeth.