Ideal for smoothies on the go, the Oasis Super Sipper insulated tumbler with silicone head straw harnesses double wall vacuum insulation technology to significantly reduce heat transfer by conduction or convection. Drinks remain cold for up to 6 hours, without condensation building on the exterior. Made from quality 18/8 grade stainless steel inside and out, this Oasis Super Sipper is highly resistant to rust, is odourless, BPA-free, and built to last a lifetime. Convenient and portable, the Sup