EXP50 expansion module (sidecar / attendant console), 60 keys (3 pages of 20 keys) with LEDs, 4.3 inch colour backlit LCD, for T53 / T53W / T54W / T57W / T58A. Note: If you use two or more SKU #EXP50 expansion modules on a single telephone, you will need to purchase (sold separately) a power supply, SKU #PS5V2000US, and connect it to the first expansion module.