This is a Sheet of 1/4" Latex Foam Rubber from Hobbico.

FEATURES:
Isolates Airborne Remote Control Units from Vibration for Prolonged radio life
Protects Fuel Tank and Helps Prevent Fuel Foaming
Made of Real Latex for more durabillity
8"x12" Sheets offer More Area than Standard 7"x9" Sheets

INCLUDES:
One 1/4" Sheet of 8" x 12" Latex Foam Rubber.