Rubber washers to prevent grease from escaping the covers on either side of the slipper bracket (i.e. the part that goes up and down and has the grease zerk). Sold each. Qty 4 Required.
 
Why aren't there seals on the covers against the frame? Those covers are sandwiched between the frame and the spring seats. There is less opportunity for grease to escape. This is also a reminder to not overgrease the slipper bracket. Don't pack the springs with grease!