Features & details HIGH BOROSILICATE GLASS: High borosilicate glass is the best! No worries with our glass jars breaking due to temperature changes. Our jars are 100% safe when heated directly from the freezer/fridge. Other baby food jars, which are made from soda lime glass, need to be at room temperature before heating or they will break. SILICONE LIDS - LEAKPROOF + AIRTIGHT: Our food grade, airtight silicone lids have been designed so your baby food is 100% safe. Airtight will keep your food fresh when stored in our glass jar. They are also leakproof, simply pop them into your bag on your days out and about with no worries with leaking. NO PAINT: To make this even safer, our jar’s measurement markings are embossed instead of painted, meaning no chemicals, because let’s face it, even the ‘safest’ paint still has to be made with something! Safe, environmentally friendly and permanent, our measurement markings won’t fade or wash off over time, unlike paint. FREEZER, MICROWAVE, DISHWASHER & OVEN SAFE - Our innovative 4oz baby food jars are made from high borosilicate glass. Borosilicate glass is thermal shock resistant, meaning our jars can go directly from the freezer or fridge to the microwave/bottle warmer or even oven. The jars and silicone lids are also dishwasher safe.