Well-known makes of reflex gauge are IGEMA,TGI Ilmadur,Penberthy, Jerguson, Klinger, and Cesare-Bonetti. Due to the caustic nature of boiler anti-scaling treatments ("water softeners"), reflex gauges tend to become relatively rapidly etched by the water and lose their effectivess at displaying the liquid level. Therefore, bi-colour gauges are recommended for certain types of boiler, particularly those operating at pressure above 60 bar.