Replacement Reagent Bottles for NT Labs Test Kits. Keep your NT Labs test kits running smoothly with our replacement reagent bottles. Designed for convenience, you can now purchase individual replacement bottles without the need to buy an entirely new test kit. Convenient Replacement: Buy just the reagent bottles you need, individually. No need to purchase a whole new test kit. Compatibility: Specifically designed to fit NT Labs test kits, ensuring seamless integration and functionality. Note: These are replacement reagent bottles only and do not include a functioning test kit. Ensure your water testing.