These chisels are manufactured from high grade hardened steel and designed to fit a wide variety of chisel plow machines. Chisel plows are most common with 1/2” holes on 2-1/4” centers although older International Harvester machines have 2-1/2” centers. Most have fifty degree shank bars. Nichols chisels are hot forged with precision countersunk holes to securely fit your machine and provide long lasting performance.