21mm black on white heat shrink tube, 3:1 shrink ratio, 1. 5m long, shrinks when heated to allow easy cable identification, recommended for use with cables between 7. 3mm to 14. 3mm, ensures a durable & easy to read result. Brother P-touch Tapes are built with tough and durable professional grade materials and adhesives. Developed to meet the needs of tradespeople and other professionals looking for reliable long-term identification that withstands the test of time. This 21mm black on white HSe-251E tape cassette has been designed specifically for the marking and identifying of cables, fibre and wires with an outside diameter of 7. 3mm to 14. 3mm. When the printed tube is placed over a cable and heated with a heat gun, the tube shrinks down, gripping the cable tightly. No adhesive is needed, ensuring that even in warm environments the heat shrink tube will not unpeel from the cable. TZe tape cassettes are quick and easy to install and come in various label widths, colours and mat