Huum Extra Small Sauna Heater Stones (3-5 cm)

Unfortunately the stones are falling apart very readily after only one use of them in the sauna. I had to replace many and will probably need to restack the stones again. I am very disappointed in these stones. they are finally the right size to fit between the elements unlike the first four boxes I ordered originally with the initial heater purchase but the quality of the stone is much different and apparently not heat stable. I was informed that using stones unapproved for the Huum heater would violate the warranty but I find it hard to believe these stones are intended for this heater. Below are pics of the fractured stones I uncovered after seeing a pile of debris beneath the heater after one use