Breaking glass is easy with these wheeled glass nippers!
Simply place the glass between the wheels and squeeze the handles. You can cut all different shapes and sizes with the nippers.
 
WARNING - SHARP GLASS.
Cup the glass in your hand or hold the glass and nipper inside of a cup when breaking to prevent shards from flying. 
Once the glass has been broken, the cut edge is sharp. Please use caution when handling sharp glass! Safety goggles are recommended.