Crain 974 Replacement Blade (4 mm) for No. 973 Rolling Hand GrooverThe Crain No. 974 is a 4 mm replacement blade for the Crain No. 973 Rolling Hand Groover. It fits both the front and rear blade positions on the 973, so a single blade type covers the entire grooving process. The 974 cuts the groove that prepares vinyl seams for heat welding, and is the same blade the No. 973 ships with. Key features 4 mm replacement blade for the Crain No. 973 Rolling Hand Groover Fits both the front and rear (back) blade positions