A polyamide masterbatch free from metal copper deposition and metal corrosion in an extruder or a molding machine, deterioration in mechanical physical properties of the product, and a color change of appearance due to water absorption and having improved heat aging resistance is produced by mixing, by melt kneading, a) 100 parts by weight of a polyamide having a water content of from 0. The new motility promoting protein macromolecule preferably has a molecular mass of 66 kda. The baffle further includes a ramp member which controls the trail edge of a sheet to maximize the beam length to reduce the bending energy which results in trail edge flip.