Preferably, the invention relates to a device, wherein {HEAD ~ the device} is smooth and without {TAIL ~ sharp edges} 
is without
Preferably , the invention relates to a device , wherein { HEAD ~ the device } is smooth and without { TAIL ~ sharp edges }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL