Measure them... there are only a few variables...
Diagonal length, width, thickness, bolt hole size, rotation direction and type of blade... :smile:KennyV
For best performance, safety and clearance/fit, I'd stick with the OEM blade(s). Get me the frame serial number off the back upper section of the mower deck, and I can then tell you the exact part numbers you need to order. The frame serial number is in the form of HXXX-1234567.
Blades are usually in-stock at most Home Depot stores and Honda Power Equipment dealers. Here's a link to find 'em in you area;