1111 / 21A00F602 Soft Vinyl Carrying Case for Handheld Refractometer BX-1, BTX-1, BX-2, BX-3, BX-4, BX-50, SX-2, NDX-2, CTX-1, and CTX-4. Color: Black. 1111L / 21A00F603 Soft Vinyl Carrying Case for Handheld Refractometers BX-10, BX-20, BTX-20, BX-90, SX-1, STX-3, and NDX-1. Color: Black.