Get THIS A/C Powered unit  NOT the battery powered unit.
My wife got me the battery powered unit for Christmas, it was good, but the battery model slows down with the slightest pressure applie...BUT the electric model is awesome, it just keep chewing through any callus you may have - something common on the hells of the flip flop/sandal wearing crowd.  This sucker will turn your cracking heels into the smoothest feet you can imagine - it's like magic.AND the resulting fine ground foot power goes for about $50 an ounce at the local Voodoo Shop.  I have no idea what they use it for, but it's a fair trade and pays for the unit in no time at all.  THAT and I've given up washing my feet altogether now.  I just grind away any dirt on my foot and when it's gone, I know the callus buildup is gone too.<br /><br />The unit is lightweight. Has a removable A/C cord and power brick (about 2&#34; x 1&#34; x 1&#34;)...lightweight none the less and a fairly long cord, I'm guessing 5&#34; so you have room to operate. The &#34;Blue&#34; sand paper buffer in the picture is released by a small sliding switch below the roller which allows you to put in new rolls.  There are three coarseness levels - Blue = Extra Coarse, Black + Super Coarse, and Green is Xtreme Coarse...I used the Xtreme to get rid of some badly cracked and thick heels - took about 20-30 mins I'd guess (didn't time it)...and as I noted, my heels are pretty smooth.  The finer grit (Extra) is goof for smaller callous and in no case do I think I wore out any of the roller buffers...they still have plenty of life even after doing both feet.  Soooo, highly recommended - from a guy who has been using a pumice stone every morning for the past twenty or so years - this thing make the whole process much quicker and easier...love it.
Rating: 5 stars