RB20/25/26 Camshaft front oil seal
Replace your front cam seals when doing your timing belt service to prevent have to do the job twice. These oil seals become dry and hard over the years of heat cycles and being soaked in oil. They're reasonably priced, and will save you the trouble of having to do the labour intensive job again.
You can also order these to go with a new set of camshafts, or a competely new engine build.
Priced individually, you will need two for a set.