DDLT003 and KDLT003 are the model numbers for this Xenon Ballast Control Unit Module. Serial numbers include 85967 52020, 85967 53040, 85967 51050, 85967 51040. Quantity: 1 pc. Function and compatibility - This module serves as the ballast control unit for D4R and D4S Xenon headlight systems, regulating power, ignition sequence, and ballast operation. - Intended as an exact control unit module replacement or repair for vehicles with D4R or D4S Xenon installations that use the listed model numbers and serials. Key attributes - Type: Xenon ballast control unit module - Identification: DDLT003 and KDLT003 with the four specified serial numbers - Condition: New or unused for replacement purposes (as provided) Practical use scenarios - Scenario 1: Replacing a faulty Xenon ballast control in a vehicle equipped with D4R or D4S lamps to restore proper ignition and light output. - Scenario 2: During headlight ballast refurbishment or diagnostic work, using the exact control unit module to ensure compatibility with original wiring and ballast. - Scenario 3: Inventory stocking for automotive repair shops or technicians who service D4R/D4S Xenon headlight systems, ensuring a correct, model-matched replacement is available. Notes - This description preserves the specified models, serials, and function without adding unsupported details.