This late ùsed genuine Hepolite piston is designed for use in Ariel 350cc 1956 -1959 motorcycles with Aluminium Cylinder heads and Red Hunters manufactured between 1933 and 1959 

This piston is the later type with Oil Scraper ring. (models NF, NH, and NG). It has a diameter of 72mm with a + 030" Oversize and a pin diameter of 20.61mm. The package includes New Old Stock Piston rings + 0.30.

Couple of scuff Mark's , see the last picture.