All of the LDH cytotoxicity assay kits work through the same mechanism. Damaged cells leak LDH which is detected through the formation of NADH. The difference between kits is how the NADH is quantitated. Most use different tetrazolium compounds (WST-1, WST-8, NBT, INT, etc.) which oxidize the NADH and are converted to highly colored formazans. Depending upon how the kits are formulated, they exhibit different linear ranges. Some formazans are less soluble and limit the upper bound of cell concentrations that can be determined. I believe that the one we produce is best, but that would probably be seen as a biased opinion.