Thermal stainless steel - keeps hot or cold for 6+ hours! We are thrilled to be the first to offer a stainless steel thermal baby bottle! Our thermal bottles feature two layers of steel. This double layering insulates the contents keeping in COLD or HOT for 6+ HOURS! No more concerns about how to warm or cool your baby's milk or formula or worrying about how to get clean, healthy hot water when you are not at home. organicKidz thermal bottles are great for play dates, travel and at day care! Versatile stainless steel lid - Lid doubles as a measuring/snack cup! Each organicKidz bottle includes a 2oz/60mL stainless steel lid that closes snug on the bottle protecting the nipple and ring from damage or dirt. The peristaltic shape allows for your baby's mouth and tongue to move in a natural, wave-like motion - just like breast feeding. Made from ultra-supple silicone with a subtle texture and shaped to fit your baby's sucking fossa, organicKidz bottles provide the optimal feeding conditions.