Auction is for a 16" or 15" White head (velum), Calf or goat, 
no difference, thickness is more important there, thinner tends to be brighter.
              THICKNESS VARIES, SO SPECIFY THIN OR THICK IF YOU DON'T WANT MEDIUM!

Please specify size when ordering! 
 The 16" size  will fit a 12" head banjo, the 15" size will work for an 11" head,
and is easier to use since since you don't have so much skin
to pull (and wrestle with)under the stretcher band.
Most banjo-ukes are typically 7" to *8"in diameter and would use the 12" size head.
You may want thin if there is very little clearance between the stretcher band and the pot/rim
Other ebay sellers don't sell new WHITE, others charge  up to $30
For Natural see my Natural auction
THE HEAD IS FOR A BANJO, BANJO MANDOLIN or BANJO UKULELE
HEADS in 2nd PICTURE, LEFT TO RIGHT ARE: WHITE, NATURAL & WHITE/16"

CALFSKIN GIVES THE MELLOWEST, WARMEST TONE OF ALL HEAD TYPES!  SOME AREAS FLUCTUATE EXTREMELY
AS FAR AS HUMIDITY GOES, SO YOU MAY WANT TO EITHER SPRAY THE SKIN WITH A WATERPROOFING AGENT
OR HAVE AN EXTRA BRIDGE OF A DIFFERENT HEIGHT (DRIER WEATHER=TIGHTER HEAD, DAMP=LOOSER) 

 * THE BANJOHANGOUT (/GROUPS/HIDEHEADS) IS A GOOD SITE FOR DISCUSSIONS ON EVERYTHING RELATING TO SKIN HEADS