Based on this product's specifications, here are some alternatives and similar models
Water test kit sera 04210 — carbonate hardness (KH) measurement, 0.015 L, hanging box
Summary description:
sera 04210 is a water test kit designed to measure carbonate hardness (KH). The kit comes in a hanging box and contains reagents for testing a small volume (0.015 L). It is intended for aquarium or pond water monitoring where KH measurement is required to manage buffering capacity and water chemistry for aquatic life.