Night Fision utilizes an injection molded process and military-grade polymer with durable polymer tritium outlines to give you flexibility and unrivaled daytime visibility. With the exception of the tritium vials, imported from Switzerland, Night Fision products are crafted end-to-end right here in the USA. This Perfect Dot night sight set is a square front green tritium with a yellow outline. It is compatible with Sig Sauer .9mm/.357 caliber P-Series models.