Safer Products for healthier babies, thinkbaby's products address the growing concern over toxic chemicals leaching from plastic baby products. All products are free of bisphenol-A (BPA), lead, PVC, phthalates, melamine, nitrosamines, and biologically toxic chemicals. The thinkbaby Stage 1 Slow Flow Cross Cut Nipples feature thinkbabys patented anti-colic system, which helps reduce gas and spit up. The anti-colic system is actually built into the nipple for easy cleaning with no little parts to lose or break. The nipple is made from extra soft, medical grade silicone and is designed to reduce collapse during nursing. The design also mimics natural breastfeeding as it requires your little one to nurse to receive fluid. The unique one-piece design eliminates cleaning headaches and tricky assembly. No extra parts to lose. The Slow Flow Cross Cut Nipples are designed for newborns to 3 months. If your child is between 3 and 6 months, we recommend our Stage 2 Medium Flow Cross Cut Nipples (sold separately). For ages 6 to 12 months, we recommend our Stage 3 Fast Flow Cross Cut Nipples (sold separately). The advantage to the cross cut design is that it is no spill! The nipples are dishwasher safe (top rack recommended). thinkbabys products are recommended by Healthy Organic Health/Child Wellnessy World. thinkbaby utilizes third-party globally certified laboratories to conduct testing. The thinkbaby Stage 1 Slow Flow Cross Cut Nipples with venting system are sold is packs of 2.