Hi
I have an HPS 18x20, and the N-Coded grommets fitted perfectly
A guy I know also got an old HPS recently, with cracked grommets, and he replaced them easily with the current 6.1 line
I believe it's the same mould since the 6.1 classic (like most Head rackets), so you can buy any generations of grommets and they will fit fine, as long as the string pattern is the same
Too bad the 6.0 95's don't work the same way...