The standard size for a bracelet screw pin for a Rolex Submariner bracelet is 1.34 mm. The diameter of the screw is also 1.34 mm. It should be noted that if replacing the screw it is important to use the correct size; otherwise, it can damage the watch or the bracelet, which may cause it to not remain closed or to become loose. Additionally, if you are returning the Submariner to its original manufacturer for any service, be sure to use the correct size screw for replacement.