Oetiker 2-ear clamps offer nearly double the clamping range, compared to 1-ear clamps. 2-ear clamps provide a degree of elasticity to accommodate changes in size of the parts being joined, such as that which may be caused by thermal expansion or vibration. As a general rule when determining the correct size 2-ear clamp the nominal size of the clamp should be chosen so that the outside diameter of the hose, measured after installation on hose stem, lies approximately in the middle of the clamping range of the clamp. Only Oetiker recommended tools should be used to properly crimp the clamp ears.