From JCW, this fire and acoustic socket box insert is 35mm deep and designed for a double socket. Pre-fabricated from Class O foam, this insert can be retrofitted into existing socket boxes or it can be fitted into new boxes. When installed in a socket box this insert will eliminate sound transfer through walls, making it a cost-effective addition to complete any acoustic build-up. JCW Fire & Acoustic Socket Box Insert Specification Depth: 35mmType: Double