In preferred form, the apparatus includes a body having {HEAD ~ a groove} with markings to define the display area and a display bar that slidably fits within {TAIL ~ the groove} 
In preferred form , the apparatus includes a body having { HEAD ~ a groove } with markings to define the display area and a display bar that slidably fits within { TAIL ~ the groove }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL