CS COSDDI Stainless Steel Insulated Tumbler

Yes, the temperature retention is genuinely impressive. Reviewers consistently mention their drinks staying hot for 4-6 hours, with some reporting their coffee was still too hot to drink after several hours. The vacuum insulation works equally well for cold drinks—iced tea stays cold all day with ice still intact hours later. Just make sure to preheat or pre-chill the tumbler for maximum performance.

It's leak-proof when the lid is screwed on correctly, but there's a catch. Multiple users emphasize you need to make sure the lid is aligned and fully tightened—if the gasket isn't seated properly, it can leak. The flip top has a locking mechanism that works well once closed, though a few reviewers found it stiff to operate. Bottom line: it won't leak in your bag if you take an extra second to ensure the lid is properly sealed.

Absolutely. This is one of those 'just right' sizes—it fits perfectly in car cup holders, backpack side pockets, and even directly under a Keurig spout for brewing straight into the tumbler. Reviewers love that it's portable without being tiny. The only caveat is if you have particularly small hands, the diameter might feel a bit wide to grip comfortably.

This is where you need realistic expectations. While the tumbler looks sleek initially, several long-term users report paint chipping after a few months of daily use, especially around the bottom and edges. If you're rough on drinkware or toss it in a bag with keys and other items, expect some cosmetic wear. The stainless steel underneath is fine—it's purely aesthetic—but if keeping it pristine matters to you, consider that trade-off.

For the money, it's hard to beat. You're getting legitimate vacuum insulation performance that rivals much pricier brands, plus it's genuinely leak-proof when used correctly. It's easy to clean, fits standard cup holders, and the rubber bottom grip prevents it from sliding around. Yes, there are premium tumblers with more durable finishes, but at this price point, most reviewers feel they're getting excellent value—especially if this is your first insulated tumbler or you need multiple for different uses.

A couple of reviewers mentioned using lead testing swabs that showed positive results, which understandably raised concerns. However, the vast majority of users have had no issues, and stainless steel tumblers from reputable sellers are generally safe for food contact. If you're particularly cautious, you could contact the manufacturer directly about certifications, or simply give it a thorough wash with hot soapy water before first use (which several reviewers recommend anyway to remove any manufacturing residue).