1. Function:The lawn mower blade balancer can provide precise blade balance, avoiding blade imbalance or bending to extend the life of the lawn mower and reduce abnormal vibration during use. 2. FITMENT:The 42 047 blade balanceer is compatible with most lawnmower blades, including Stihl/Troy/Husqvarna lawn mower blades. Replace 42 047/339075B lawnmower blade balancer. 3. EASY TO USE:Insert the hole in the center of your blade right on the tool; Push the back part and then the magnets stick onto the blade; If it's unbalanced it's going to go either to one side or the other, so you need to clean off your blade or shave off your blade before balancing. When the blade is horizontal, it's balanced. 4. :With six magnets for better stability. PLEASE NOTE: When installing the balancer, please make sure there is enough space on both sides so that the blade can rotate 360 degrees without being obstructed or touching anything.