Genuine Casio replacement rubber packing/o-ring in black. 
 
Made for the following model(s):
GA-2000HC-3A, GA-2000HC-7A, GA-2000SKE-8A, GA-2000WM-1A, GA-800DC-1A, GA-835A-1A, GA-810GBX-1A9, GA-800SC-2A, GA-800LT-1A, GA-2000SU-2A, GA-2000SU-1A, GA-2000BT-1A, GA-800-1A, GA-800-4A, GA-800SC-6A, GA-800SC-7A, GA-810B-1A4, GA-810B-1A9, GA-800CG-1A, GA-810GBX-1A4, GA-810MMB-1A2, GA-810MMA-1A, GA-835E-7A, GA-800BR-1A, GA-800CC-2A, GA-800MMC-1A, GA-2000-1A2, GA-2000-1A9, GA-2000-2A, GA-2000-3A, GA-2000-5A, GA-2000E-4, GA-2000S-1A, GA-2000GZ-3A, GA-2000S-7A, GA-800BL-1A
 
GBA-800DG-1A, GBA-800AT-1A, GBA-800SF-1A,  GBA-800LU-1A1, GBA-800LU-1A, GBA-800-1A, GBA-800-7A, GBA-800-8A, GBA-800-3A, GBA-800-2A, GBA-800-9A, GBA-800-2A2, GBA-800-4A, GBA-800DG-2A, GBA-800DG-7A, GBA-800DG-9A, GBA-800UC-2A, GBA-800UC-5A, GBA-800EL-4A,
 
GBD-800SLG-3, GBD-800SF-1, GBD-800LU-9, GBD-800LU-1,GBD-800-4, GBD-800-1, GBD-800-2, GBD-800-8, GBD-800-1B, GBD-800-7, GBD-800UC-3, GBD-800UC-8, GBD-800UC-5,