Mark inner diameter × outer diameter × thickness. The oil sealing disc is an accessory, which is installed at the end of the shaft to prevent lubricant from flowing out of the gap between the shaft and the box. There are many types of oil seals, and the marking methods are similar. Generally, the nominal size of the structure is marked. For example, the skeleton oil seal is generally marked with inner diameter × outer diameter × thickness. For example, O-rings are generally marked with inner diameter × section diameter.