4228A-1 is part of 4228A or closed look of 4228A. 4228A-1 is cut from 4228A. I use 4228A-1 to check the detail quality of 4228A. 4228B-1 is part of 4228B or closed look of 4228B. 4228B-1 is cut from 4228B. I use 4228B-1 to check the detail quality of 4228B. 4228A and 4228A-1 is thestandard sample of silver running board. 4228B and 4228B-1 is thestandard sample of black running board.