The Smikkels straw cap is made of food-grade (PP) plastic, so it is free of BPA and PVC. It fits both our regular stainless steel water bottle and our thermos water bottle. Available in warm white and black. You get a handy brush to keep the straw clean. In addition to this cap, we also have a convenient regular cap for your water bottle. Since we have different sizes of bottles, you need to trim it to size by cutting off a piece. For this, the packaging includes a handy ruler.