These Short Waterproof Screw Top Vials are great for all those needs when packaging a first aid kit. They can used to carry medications in a first aid kit or be utilized for anything in a survival kit like a small fishing tackle kit . Being food grade, they can also be used to carry salt, pepper, spices, etc. in your cook kit! You can buy each size individually as a three pack or a three pack with one of each size! All three vials are 2-3/16" long, with an inside length of 2-1/8". The small vial measures 11/16 diameter (inside) and 7/8" diameter (outside cap). The medium vial measures 13/16" diameter (inside) and 1" diameter (outside cap). The large vial measures 7/8" diameter (inside) and 1-1/8" diameter (outside cap). There are so many uses for these vials that you will be surprised you went without them.