Rotary Evolution replacement blades are made of black etched carbon steel. The set contains 9 blades and the screws that go with them, so a blade change is done in one go without hunting for fasteners.
The set replaces Stihl Basic IA000074202 and Duro Plus IA000074206, IA000074207 and fits Stihl iMOW 3, 3 EVO, 4, 4 EVO, 5, 5 EVO, 6 EVO, 7 and 7 EVO.
Change all blades at the same time. A robotic mower runs with its blades balanced against each other, and a single new blade among worn ones makes the disc run unevenly.