Determine hose OD or hose bundle OD. If needed find the circumference of the hose or bundle of hoses, then calculate diameter. Also assess if the hose or hoses have bends or movement during application as the sleeve will need to be over sized to accommodate. Sizing a sleeve to tight to the hose or bundle of hoses will hinder natural movement of the hose within the sleeve, causing premature hose failure due to possible abrasion. Typically size the sleeve 1 - 2 sizes bigger than your current hose or hose bundle OD.