small air valve used in inflatable materials like camping mats

[welby51]

I am trying to find a manufacturer of the type of air valve used by Thermarest for their camping mats. First of all, does anyone know what the industry name for that type of valve is? It seals by twisting the valve, and allows airflow both ways when opened. Secondly, can anyone point me to a website for a company that would carry this type of valve for sale?

Thanks