NITRILE BONDED RUBBERISED CORK SHEET TYP [ NITRILE BONDED RUBBERISED CORK SHEET TYPE RC 70 C VERY GOOD OIL RESISTANCE FOR MAIN TRANSFORMER THICKNESS 12MM OF SIZE 900X600 TO IS SPECN 4253/ PART II- 1980 ( REAFFIRMED 1999 ) EDITION 2. 3 ( 1993- 11 ). ]