The used Lexar 256GB Professional 3400X 510MB/s CFast 2.0 is an ultra-fast memory card designed for 4K video cameras that use the CFast 2.0 format. Key features include:

CFast Format. The Lexar 256GB Professional 3400X 510MB/s CFast 2.0 memory card’s format is a pinless design that offers extremely fast read and write speeds. This card is only compatible with CFast-capable camcorders.

510 MB/s Read, 450 MB/s Write. The ultra-fast speed supports burst shooting and 4K RAW capture.