Description thinkbaby's products address the growing concern over plastics leaching toxic chemicals.  Using a team of physicians and scientists, thinkbaby has found safer materials to use for all of their baby products.  Because research has linked many chemicals in common use to cancer and hormone disruption, thinkbaby does extensive product testing to bring you the safest products available. thinkbaby products are made of Polypropylene (PP), which is a medical grade plastic and can easily be recycled at most recycling locations. PP is safe and free of Bisphenol-A (BPA), lead, PVC, phthalates, nitrosamines and biologically toxic chemicals. All thinkbaby products are FREE of BISPHENOL-A (BPA), PVC, LEAD, PTHALATES, and NITROSAMINES.  Their products have been tested globally by third-party labs and are also packaged in recycled materials. thinkbaby has a patented venting system for their bottles which reduces colic and spit up.  This venting system has even been shown to reduce risk of middle-ear infections.  The venting system allows air to flow back into the bottle reducing the vacuum created while your child is nursing.  Available are 2 packs of 5 oz bottles with Stage A (Slow Flow) nipples, 9 oz single bottles with either Stage A or B nipples, 9 oz Sippy Cups and the Conversion/Replacement Kit. Stage A Nipples - Slow Flow - 0-6 months Stage B Nipples - Fast Flow - 6+ months thinkbaby's nipples are made of a high grade silicone that is extra soft but does not collapse, making transition from breastfeeding to bottle feeding easier.  The cross cut pattern means milk only flows when gentle pressure is applied to the nipple.  Slow Flow nipples generally are used for younger babies, and the Fast Flow nipples are used for older babies.  Slow flow nipples are included in the 2 packs of bottles.  Due to hygiene reasons we do not accept returns on used nipples. thinkbaby's 9 ounce Sippy Cup has an extra soft high grade silicone spout which provides easier transition from bottle feeding to cups.  The handles make it easy for little hands to hold. thinkbaby bottles and Sippy Cups have travel caps to prevent spills when on the go.  Their products are top rack dishwasher safe. Now you can use the thinkbaby Conversion/Replacement Kit to quickly convert thinkbaby bottles into a thinkbaby Sippy Cup! This Conversion Kit is designed to fit all 5 oz and 9 oz thinkbaby bottles. Included are 2 No Spill spouts and 1 Sippy Cup handle. The spout is an extra soft, medical grade for easy transition from the bottle to a Sippy Cup. Perfect for 9 - 36 months! Because you are reusing the thinkbaby bottles, you will reduce environmental waste and save money!