The sapphire crystal is in perfect condition, the bezel rotates, the time and date can be set via the crown. The case and bezel only have minimal marks. Whilst this is rated to 300m water resistance I would advise a pressure check before you took it into any water. As for time keeping this watch has been running for me at about +4 to 6 seconds per day so well within it's chronometer status.
Bear in mind this may alter depending on how someone wears a watch, how wound the mainspring is kept and resting positions the watch is left in. The power reserve is excellent. The wave dial is in amazing condition, as standard on older Seamasters the red tip of the seconds hand has faded. The watch itself comes on it's original bracelet which is currently sized to my 6.75 inch wrist. There are no extra links although links for this bracelet are plentiful and not expensive.The diver's extension on the clasp works perfectly as does the clasp. The bracelet itself is in excellent condition and only has minimal stretch. As a point of Trivia this is the 36mm version of the watch Pierce Brosnan wore as James Bond in Die Another Day. The item "Omega 300m Mid Size Seamaster Chronometer Dive Watch 2551.80.00 Full Set" is in sale since Sunday, September 5, 2021. This item is in the category "Jewellery & Watches\Watches, Parts & Accessories\Watches\Wristwatches".
The seller is "sir_cortez" and is located in Oxfordshire. This item can be shipped to United Kingdom, Australia, United States, Bahrain, Canada, Japan, New Zealand, China, Israel, Hong Kong, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Taiwan, Thailand, Bangladesh, Bermuda, Bolivia, Barbados, Brunei darussalam, Cayman islands, Egypt, Guernsey, Gibraltar, Guadeloupe, French guiana, Iceland, Jersey, Jordan, Cambodia, Liechtenstein, Sri lanka, Macao, Monaco, Maldives, Martinique, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Saudi arabia, South africa, United arab emirates, Ukraine, Bahamas, Colombia, Jamaica, Kuwait, Panama, Philippines, Qatar, Uruguay.