Here is the replacement piston ring ATHENA 165cc Ø69mm mounted on HONDA CRF 150cc. These rings are mounted on the dimension A, B, C, ... of your piston. Ideal if you consume oil for example. If you have a strong loss of compressions we advise you to change the piston for the dimension above. Don't forget to change your seals for a tight reassembly and thus an increased reliability