As a convenience for our customers GT Products offers this precise scale. All of GT Products silicones should be measured by weight and the ratio is critical to achieving the strongest and longest lasting molds possible. Over catalyzing can cause the silicone to become brittle while under catalyzing can cause the material to not set up properly or not harden at all which could destroy the substrate that the silicone is poured against. This scale is extremely easy to use and is compact and portable. 2 AA batteries are included.