I had ordered a pair of these Merell Men's Moc Slip-On Shoes in size 15M a few years back and they fit very comfortably.  Most recent order for the Merrell Men's Moc Slip-On $79.95, Free Shipping.  Trying on this newer pair in the identical 15M size was a challenge, as they were just too small, too tight.  After walking less than 10 feet on the carpet, had to box them up and ship them back. Tried to find the same Moc Slip-On in a slightly larger size 16M, $86+, but only available in a dark color and additional shipping is $22+ from UK.  Will keep trying to find a pair that fits.