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