20 PLYSIL® Silicone Rubber Tape A 20 mil (0.51 mm) triangular cross-section, self-amalgamating, silicone rubber tape used for jacketing high voltage terminations on solid dielectric cable through 69 kV. 20 Plysil is track and erosion resistant and can be used as primary insulation for high temperature (180 deg C) applications. ASTM-D-2148, MIL-I-46852A.