Beauty mixing accessories MUST be inert (neutral) to ingredients. This is the only way to ensure your ingredients do not react to the accessory, oxidize the recipe and alter recipe's pH (the most critical aspect of any beauty recipe). And using non-plastic, stunning handmade glass is always more fun and feels great - on your hands and for our planet. Measuring 2.5" x 1.5", it is a beautiful option for a variety of recipes and anything else you might think of. Just use caution - this IS pure glass, without any plastic... and it is, as it should be... fragile. But it is heat resistant and dishwasher-safe. Watch our video about making of our glass. Katari Beauty | we travel and source all our single-ingredient ancient Mediterranean staples from the artisans we work with. We package it all in hand blown glass we make. We believe in slow beauty and a more sustainable world.