Set of 4 photoetch saw blades.  3 fit Xacto handles.  The bottom is for a cheap box cutter but works great in the large Fiskars hobby knife handle. 
If you've ordered my photoetch before you know that I use a thicker metal than most.  And as a fan of photoetch saw blades, thought it was only fitting that I did some of my own, using some cool knife designs. Anyways, I tested them out and they seem to be a bit more rigid than the other 4 brands I've tried.  They're perfect for cutting doors or grilles out. 
*I highly recommend using a photoetch saw blade of any brand for cutting into resin doors and trunks. Resin is softer than styrene and Xacto blades can widen that gap pretty easily.