Andis® UltraEdge Size 40 0.25mm Blades are made from carbon infused steel for superior cutting and long life. Preferred by veterinarians,  Length of cut is 0.25 mm.

This is a detachable, A5 style, finish cut blade. 

Finish Cut: Longer blades come in 2 teeth types: FC or F which both stand for Finish Cut - or ST which means Skip Tooth. Shorter blades only come in FC. Unless experienced using ST blades, use FC.

A5 style: A5 blades are standard fit blades for use with all brands of A5 model clippers, including Andis, Wahl, Heiniger, Oster & more. Important: Not all clippers by those brands are A5 models.