Shrink ratios dictate how much the sleeve shrinks during final heat application steps. Standard ratios range from two-to-one up to four-to-one for fitting over large connectors. High shrink ratios allow smooth placement over bulky terminal ends before recovering tightly. Using Teflon Shrink Tubing ensures a tight protective skin over irregular metal geometries. Proper sizing prevents loose sleeves, air gaps, and uneven thermal protection along wires.