The one or more additional sensors are for sensing, for example, a piece of environmental information in {HEAD ~ the immediate vicinity} of {TAIL ~ the hydration sensor} 
The one or more additional sensors are for sensing , for example , a piece of environmental information in { HEAD ~ the immediate vicinity } of { TAIL ~ the hydration sensor }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL