REI.com has 21 oz Hydro Flask Stainless Steel/Standard Mouth Water Bottles in 7 different colors on sale for $18.93. (32% off from original of $27.95).
Hydro Flask Standard-Mouth Vacuum Water Bottle – 21 fl. oz. (available in 7 different colors)
The 21 fl. oz. Hydro Flask Standard-Mouth vacuum water bottle keeps hot drinks hot for 12 hrs. and cold drinks cold for 24 hrs. Fill it with ice water at 8 a.m. and have a cold drink the next morning!