RO CAPS IN 31.5 MM BLACK METAL These lovely coloured closures enhance the appeal of our FSSC 22000-certified and food-grade glass bottles. These caps are the most effective and keep your products secure in our glass containers made of lead- and toxin-free material for a very long time. Even when the product or liquid is shaken upside down, these caps and closures provide a perfect, leak-proof seal. Not only that, but we also provide customization choices in addition to our caps and closures, which raises the perceived worth of a product.