Other sensors can use {HEAD ~ LEDs} tuned to {TAIL ~ frequencies} which are absorbed in different amounts by the gases typically used for welding 
tuned to
Other sensors can use { HEAD ~ LEDs } tuned to { TAIL ~ frequencies } which are absorbed in different amounts by the gases typically used for welding
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH