Please note that all fees (Shipping, Taxes, Duties, Etc.) associated with international returns and exchanges are the responsibility of the customer.Available in 3 sizes with unique "key" that prevents theft of any seatpost. Keep your Kinekt seatpost safe from prying eyes! Lightweight and durable. Made from 6061 High quality Aluminum. Choosing the correct locking collar for your bike.When purchasing our Kinekt Locking Collar to keep your seat post safe, you will need to know the size of the seat post collar already installed on your bike. The best way to find this is to remove your seat post from your bike, remove the collar from your frame and check the size printed on your collar like seen in product photos.Please know that you are purchasing the size that will fit onto the frame of your bike. Do not go off the size of the actual seatpost. If the orginal collar on your bike does not have a size printed, please reach out to your bikes manufacturer to find out the collar size or you will need to measure the outside diameter of the seat post tube to get this measurement. Sizes avalible for the Kinekt Locking Collar.28.6mm size fits seat tube size ranges up to 29.6 mm31.8mm size fits seat tube size ranges up to 32.8 mm34.9mm size fits seat tube size ranges up to 35.9 mm