K-FLEX INSUL-SHEET rubber sheet rolls for insulation.  K-FLEX INSUL-SHEET is a flexible, closed-cell elastomeric sheet insulation product used to conserve energy and prevent condensation on large pipes, ducts (covers), vessels, tanks and equipment. The product’s closed-cell structure creates exceptional thermal properties (k-value of 0.245 at 75°F and wvt of 0.03 perm-in) that protect against moisture penetration and heat loss or gain within a -297°F to 220°F temperature range.