The unusually high 4:1 shrink ratio of this tubing along with built-in adhesive ensures an air tight, water tight joint sealing out corrosion from wiring connections. Fits wires just under 1/4in. (.225in.) and smaller. Just use a heat gun, lighter, or match to shrink tubing onto connector and activate adhesive. includes 10 lengths of shrink tube 3in. long (enough to seal connections under the hood and car on most vehicles) and complete intructions on package.