We use nylon paracord made in Europe or America. Color customization is available. Collars: With BioThane adjusters, up to 35cm neck size (Sizes larger than that will be an additional 500 yen per 10cm) (Half-choke type collars will be discounted by 800 yen) Leashes: 8-strand braid, up to 120cm, using a snap hook for large dogs (Changing to 6-strand or 4-strand braid will result in a discount) The colors in the image are: Black, Indigo, Polar Blue, Silver Gray Leashes only or collars only are also available. We will make them in your favorite colors, so please comment. Thank you for viewing.