What Does A Npk G Concret Crusher Fit. NPK CONSTRUCTION EQUIPMENT, INC. ("NPK") warrants that Boom Mounted Material Processors, Concrete Crushers, and Shears sold by NPK will be free from defects in material or workmanship for a period of six (6) months or 600 operating hours, whichever occurs fi rst, starting from the date of delivery to the fi rst user.