A protective insert for protecting e.g. coils or rolls of sheet steel or aluminum is disclosed. The protective insert is open and diametrically adjustable. The ends of the protective insert may be adjustably engaged by means of engagement means. The engagement means permit diametrical adjustment and locking of the diameter of the protective insert to a suitable diameter. A method of protecting a portion of an object, in particular a roll of sheet material, having a hollow core, is also disclosed.