The 300W 500W aquarium heater quartz glass tube is the heater rod part for HG-925 aquarium heater.<br> Please not that the heater tube can only be used with the HG-925 hygger aquarium heater controller.<br> Here is the ASINS for the HG-925 aquarium heater:<br> The 300W aquarium heater tube is for ASIN B08S3Q282Q<br> The 500W aquarium heater tube is for ASIN B08S3SV7KR <br> The length of the heater tube:<br> 300W: 7.7inch<br>500W: 10.5inch<br><br> Voltage: 110-120V/60HZ<br>