Carefully selected by a famous Japanese carpenter. The blades of these particular saws are replaceable and are held securely in the wrapped handle by a simple screw. One edge has teeth for ripping, with smaller teeth near the handle to use when starting the cut, before bringing the full effective edge to bear on the workpiece. The other edge has crosscut teeth which produce a wonderfully clean cut surface. The centre of the blade is scraped to be thinner than the edges so as to prevent binding in a deep cut. The word 'replaceable' might conjure up an image of a mass produced item. In actual fact every blade is checked and hand finished before leaving the manufacturer. These saws are made for the professional Japanese market so there is no compromise on quality. Two sizes are available 195mm and 240mm, the longer of the two having slightly coarser teeth. Tpi is not really relevant in this case, the heavier the work the longer the saw, either of these offered here suit the vast majority of tasks.