A premium stainless steel tumbler Unlike inferior travel mugs, this premium 25 Oz insulated tumbler from Hydrapeak is made from the highest grade 18/8 food grade stainless steel. We researched common complaints about other travel coffee mugs and carefully crafted one of the best stainless steel tumblers on the market. With meticulous craftsmanship and razor sharp design, the Hydrapeak tumbler with lid and straw is second to none.