The HUNTER 221200 I-25 Riser Seal is designed to work in the Hunter I-25 series and will not work with other sprinkler heads. It is used solely for the replacement of the seal. There is no need to replace the spring seat.A common reason for a rotor sprinkler to start leaking between the pop-up riser assembly and the body cap while it is in operation is because the riser seal is worn or there is debris between the seal and the riser.Hunter Industries is a global manufacturer of a full range of high-quality irrigation products from controllers, rotors, rotary sprinklers, spray head sprinklers, nozzles, valves, weather drips and much more.How to install:
Expose the top of the rotor sprinkler & unscrew the lid (you will be removing the entire inner assembly)
Place sprinkler on a hard surface, stretch the spring downwards, with the palm of your hand over the rubber cap, use 4 fingers to lift upward & snap off the top cap (keep spring depressed in a downward position) 
Remove the soft rubber seal first & then the hard plastic seal
Place the new hard plastic seal on with the channel facing downwards, repeat with soft rubber seal
Slide down the soft rubber seal below the seam of the turret & the body
Take the cap & force it over the top to close & release pressure of the spring
Re-set the positioning & place it into the body cup of the sprinkler & lock in place
Product specifications:
Weight: 0.1kg
Colour: Grey
Dimensions: 4.5 × 4.5 × 0.01cm
Watch how to replace a Hunter Riser Seal