Mantec fitting guides & spares › 926-PSNWA 1 / 2 Image 1 of 2 Image 2 of 2 926-PSNWA £1.80 sold out Piston washer; replacement recommended on sign of wear, tightness or looseness in the piston action. Sold Out Added! Piston washer; replacement recommended on sign of wear, tightness or looseness in the piston action.