Seiko Case Back Gasket Seal 1 part ( FH2920B03 ) see list below
£9.75
I have collected Seiko watches for 50 years. For sale, 1 Flat Gasket Seal Ring (0.5 mm thick). I can check you have the correct part, or give you the correct part number. I can pre-grease you gasket/seal, silicon grease, just ask.