Pro Liner 5MM Dual Layer Sound Deadening. 2mm Skinz Sound Deadening with 3mm Skinz Liner 12 Sheets: 375mm x 480mm x 5mm – 2.20 sqm. This dual technology solution offers a lightweight alternative to using separate sound deadening and panel liner. Primarily for use where space is tight, this dual solution offers the best way to prepare a car for audio.