Accusize Industrial Tools18 Pc Angle Gauge Set, 3602-5050

Q: The 5, 10 and 15 degree tool have no notch to insert a blade into... which would be very important to me. How do you use this for those angles?

I guess you could stick the point of another size, e.g. 40-degree, into the notch of a larger size, e.g. 45/50/55-degree. Then stick your blade into the remaining opening in the notch. Not ideal but I guess they thought they couldn't machine that narrow of a notch on its own.