This Specific Gravity Combo Kit has everything you need for testing the gravity of your brews.  Testing the gravity of your brews determines the ABV of your beer and is the ONLY way to ensure that fermentation has finished.
 
The kit includes a plastic hydrometer test cylinder with a removable base, a glass triple scale hydrometer, a dual scale liquid crystal stick on thermometer, and test jar saver (so you can KEEP testing in case your cylinder takes a tumble), and full instructions on opertating and accurately reading your hydrometer.