Welcome to the wonderful but slightly bizarre world of casein. If you've never played this amazing material (but have heard about it), you're in for a real treat. When I started Charmed Life I had no plans for anything other than the brown series. Then I played casein and my world changed.
Reminiscent of genuine tortoise shell (now highly illegal), casein is noted for its tonal warmth, balance, detail and quietness across the strings. As a player of TS for over forty years, I can tell you that this is the closest thing I've found in more than four decades of searching.
The nf-1.15 is a classic 351 teardrop shape at 1.15 mm thickness (plus or minus about .05 mm, due to hand finishing and polishing). And it's pretty too.
PLEASE NOTE: These are extremely hard to make. Average lead time is two to three weeks. Sorry we can't peddle faster.