Also known as Bet R Grip and Quad Lobe, they are the most comfortable true hard handle drivers I've ever held. I've been on a mission to complete the set. As of now I've got 38 out of 43 styles of screwdrivers.
The composite material that's used in the handles is pyroxalin, a nitro-cellulose plastic form the early days of organic chemistry. IIRC it is related to the explosive gun cotton and old celluloid film base. It doesn't degrade and stink like the newer acetate plastics do, but it might burn.
Anyway, here's my set, followed by some specialty styles I've managed to find (gasket scraper, cotter pin remover, schrader valve core remover, 1/4" drive handle).
The ones I'm needing: 9625, 9626, 9633, 9805, and 9810