Micron filter replacement Fits Hill MK4 hand pump only* Easy to replace Instructions: Unscrew the hexagonal connector on top of the base housing (to remove pump) Remove the filter from its seat in the bottom of the housing Place the replacement filter into the housing Replace the o-ring, if needed Reattach the pump and tighten the hexagonal connector Maintain your Hill hand pump, and it'll always be reliable. Replacing the filter is essential for proper functioning of the pump. *For pre-MK4 micron filter replacements, see PY-A-3889.