Johns Manville Whispertone® Wallboard is manufactured using fine, rotary process glass fibers bonded with a thermosetting resin to produce a structurally rigid board insulation. The top surface is smooth and uniform in color and can be produced either plain or with a EvalithTM mat facing. Whispertone Wallboard is designed for use in a wide range of acoustical panel and office interior product applications and HVAC equipment. In addition, it is, resilient and resists settling, breakdown, sagging from vibration and damage from impact.