What brands do manufacturers of passive oxygen laser detection in coal mines have?

At present, the well-known brands of underground gas detection in coal mines are: Japanese Riken Keiki, American RKI Instrument and German DR. Ger and GfG in Germany and MSA security in Germany are relatively economical brands for underground gas detection: Shandong Hanhua, Shandong Jie Bao, Anhui Ying Ying, Zhejiang Preger, Jiangsu Chi Jia, Jiangsu Xinyuan, Sichuan Mingyu and Chongqing Puyi.