The 38mm deep with 23mm width are available. The size is 572mm(ERD),weight is 430g+/-10g/Piece. But the brake surface is not basalt. It is high-temperature resisting brake surface.
Still not on the web page under rims.
Also, slight spelling mistake on the Accessories tab. I was wondering what "Steam" was, and had a laugh when some 'stems' popped up