Sile it is! Thanks. Once you guys gave me a name, I was able to find lots of photos online confirming your ID.
I recently purchased a 1968 Model 17-3 with medium size non-adjustable Nill target grips that were a little too small for me. I think these Sile grips will be a little less confining.
Late last year I bought a Model 16-4 with Herrett target grips, also a little too small and non-adjustable. I replaced those with original Lew Horton goncalo alves grips.