Genuine Casio replacement rubber packing/o-ring in black. 
 
Made for the following model(s):
AMW-103B-1AV, AMW-103B-3AV, AMW-103D-7AV, AMW-103D-5AV, AMW-103D-1AV, AW-560-1B2V, AW-560B-1AV, AW-560-1B3V, AW-560D-7CV, AW-560E-1AV,
 
ECB-500DC-1A, ECB-500D-1A, ECW-M300EDB-1A, ECW-M300-1A, ECW-M300E-1A, ECW-M300DB-1A, 
 
GST-B100GC-1A, GST-B100GA-1A, GST-B100RH-1A, GST-B100D-1A9, GST-B100BNR-1A, GST-B100-1A, GST-B100B-1A4, GST-B100B-1A3, GST-B100X-1A, GST-B100TFB-1A, GST-B100XA-1A, GST-B100XB-2A, GST-B100D-2A, GST-B100D-1A, GST-B100G-2A