The Temperature tape works best and lasts the longest when applied to a clean and FLAT surface. Watch the video below for full applications instructions! Never guess what the water temperature is with temperature tape. This thermometer securely fastens to your fishing net or any other smooth surface and tells you the exact water temperature within 1-2 degrees. This thermometer also features a "safe zone" outlined in green, a "warning zone" outlined in yellow, and a "danger zone" outlined in red to ensure the user is aware of when the water temps are safe for trout and when they&';re not! Easy to read and Easy to use this thermometer is sure to keep the trout safe. Farenheit