Hello! This listing is for 1 (one) K23-406 Trailer Brake assembly fits Dexter axles 15k with hydraulic brake on the Left hand (Drivers side). This unit has a diameter of 12.25'' by 5'' wide. It uses 7 bolts to secure to the axle. We also stock wheel seals, premium Koyo (made in Japan) bearings, plastic oil caps, brake drums and much more. This unit is common to use the 9-28 brake drum listing number 275378727467. Please know we strive and do ship virtually all products same day! You can always feel free to message us to be sure! Thank you for checking us out! We look forward to serving you! The right hand brake assembly is listing number 275480648780.