These blades are designed to fit my marking knives.
This particular style, the SM01 Blade is what I recommend for use in the knife as I find it promotes a very ergonomic cutting angle with a long reach on the blade. Perfect for getting deep into joints for layout, and thanks to the rigidity of these razor sharp blades, are great for cleaning debris from corners too.
Please note that it is much more cost effective to purchase these directly from Swann Morton! The reason I'm listing them here is by request, mainly to make them more convenient for customers to purchase and have the ability to combine delivery costs.