Concave consists of main frame and 7 clover boron max thresh inserts. The clover insert is our maximum threshing insert, and it is used in extremely hard thresh conditions. Used in crops like grass seeds, flax, durum and hard-to-thresh wheat varieties. This insert is typically installed into the front concaves in limited numbers or ordered as a full concave. These inserts are individually replaceable, 180-degree reversible and boronized to extend the life of the insert. Boronizing is a thermo-chemical hardening process used to improve the life and performance of metal components to strengthen resistance to corrosion and abrasive wear.