Selling this aftermarket caseback which fits 3861 speedmasters. This is a popular mod for especially hesalite speedmaster which do not have a window to the movement from the factory. additionally, it result in a small decrease in overall thickness. This one that I'm selling was used for about 3 or 4 months and is in immaculate condition. Caseback only. More info here: https://www.spiralwinderwatchparts.com/product-page/sapphire-exhibition-caseback-for-the-3861-omega-speedmaster ~~Asking $80, shipping included~~ sold