This listing includes five duplex lever springs, part number RC4-3245 (also referenced as RC4-3245-000CN).These components are compatible with printer models M402, M403, M426, M427, M501, M506, and M527.The parts also fit model series 402, 403, 426, 427, 501, 506, and 527.This spring is designed to restore function in the duplex lever mechanism.