Davis Instruments Air-Flow Tels - Set of 14. No holes required. Tels show the air flow across the sails - allowing you to trim sails for maximum performance. Each kit includes 14 Tels and full instructions on where to apply them and how to read them. Specifications for Davis Instruments Air-Flow Tels: Manufacturer: Davis Instruments Color: Black Package Contents: Davis Instruments Air-Flow Tels Davis Instruments 950: Air-Flow Tels - Set of 14