Keystone Electronics Corp. TO-66 Transistor Insulator 4666

The 4666 transistor insulator is designed for TO-66 cases, featuring a hole pattern with 'M' diameter of 0.780 inches (19.9 mm) and 'L' diameter of 1.375 inches (34.9 mm). It is made from glass-filled polyester with a UL 94-V0 rating, providing thermal conductivity and electrical insulation for power transistor mounting. The insulator is part of a series compatible with TO-66 packages, and its dimensions and material conform to standard mounting requirements for this case type.