Polk Audio DB651 6.5-inch 2-Way Coaxial Speaker (Silver) The DB 651 come with 6 3/4-inch adaptor rings for easy fit in VWs, Audis, BMWs and other European cars. This is a truly versatile high-performance coaxial loudspeaker with all the polk features and technology that make it a great choice for any vehicle. dimensions - cut-out diameter 5 (12. 70cm) inch dimensions full-range mounting depth - bottom mount 2 3/8 (6. 03cm) inch dimensions full-range mounting depth - top mount 2 (5. 08cm) inch dimensions grille - height 1 3/16 (3. 02cm) inch driver complement mid/ woofer - diameter 6 1/2 (16. 51cm) inch driver complement mid/ woofer - quantity 1driver complement mid/ woofer - type dynamic balance driver with polymer/mica composite cone with rubber surround driver complement tweeter - diameter 3/4 (1. 91cm) inch driver complement tweeter - quantity 1driver complement tweeter - type silk/polymer composite dome electrical - efficiency 92 DB electrical - nominal impedance 4 ohm electrical - total frequency response 35 hz -22k hz electrical power handling.