BACKUP O-RING, MATERIAL BUNA-N, FOR USE WITH AS568A DASH NO. 284, THICKNESS 0.05 IN, RADIUS 0.174 IN, AXIAL THICKNESS 0.04 IN, ACTUAL WIDTH 0.118 IN, ACTUAL INSIDE DIA. 17.989 IN, CROSS SECTION SHAPE RECTANGULAR, DUROMETER 90A, DUROMETER (HARDNESS) RATING HARD, COLOR BLACK, TEMP. RANGE -40 DEGREES TO 250 DEGREES F, PACKAGE QUANTITY 5