Insulation type: Double wall; Temperature retention: Yes ; No sweat Exterior (Keeps liquid hot/cold upto 6 hrs hot 12 hrs cold); Leak proof: Yes; Wide Mouth 60mm for easy cleaning Inner and Outer side of mug is made from 304 Grade Steel which is Rust Free and 100% Food Grade. Strong handle, making grip comfortable and Leak proof screw Lid design with Silicon seal makes it spill proof.