1.It is fairly easy to use，a great system to track our Oxygen and Nitrous tank usage. 2.Sometimes it's hard to figure out which ones have been used or not. These tags are easy to twist on to the tanks and take the guesswork out of the equation. 3.There are 3 parts in the cylinder tags marks“Full”“In Use”“Empty” 4.Bright color colors are easy to identify. 5.Each tag measures 4x2 inch,100 pcs per pack.