This set of six ignition coils and OEM spark plugs is designed for Buick, Cadillac CTS, and GMC 3.6L engines. The coils have four-pin connectors and male terminals with blades, while the female connection gender ensures a secure fit. These ignition coils are made by MAS and ACDelco and come with a one-year warranty. They are interchangeable with part numbers 12583514, 12613051, 12613057, 12629037, 921-2075, 50136, 178-8489, 36-8161, 52-1816, C1508, CUF375, 5C1551, 5C1612, and C-747. The set also includes other part numbers such as UF375, UF-375, D501C, D510A, 5C1551, and E405. This is a great value for anyone looking to upgrade their ignition system.