16 mm inner diameter (shaft), 30 mm outer diameter (housing), 7 mm width. Dimensions are brand-independent; measure the inner diameter, outer diameter and width with a caliper to verify your part.
For seals, material (NBR, Viton/FKM) and lip type (single / double lip, dust lip) matter as well as size; choose by temperature and lubricant.
If you are not sure, send us a photo of the part or the code on it; we will find the right product and price.