GSI Outdoors Microlite 350 Flip Water Bottle Fuchsia, One Size

Stainless steel makes it rugged and pure, the vacuum-insulation keeps hot drinks hot for 12 hours and cold drinks cold for 24, and the insanely thin 2mm walls keep the profile trim enough for cupholders and other tight spaces. The cap is amazing. Lock it tight for travel, then push a button and it flips up for easy drinking.