SIERRA Air Filter 23-1101 23-1101 Air Filter Replaces: Westerbeke 39705 Fits: 8.0 BTDA(60Hz) / 6.0 BTDA(50Hz), 10.0 BTDA(60Hz) / 7.5 BTDA(50Hz), 10.0 EDT(60Hz) / 7.5 EDT(50Hz), 11.5 EDT(60Hz) / 9.2 EDT(50Hz), 12.5 BTDB(60Hz) / 9.4 BTDB(50Hz), 12.5 EDT(60Hz) / 9.4 EDT(50Hz), 15.0 BTDC(60Hz) / 12.0 BTDC(50Hz), 15.0 EDT(60Hz) / 12.0 EDT(50Hz)