I've worn 7.5 Merrell boots/shoes for years so figured size wouldn't be a problem.  They arrived on time but were way too big even though marked as 7.5.  When I asked about returning or exchanging them I was told by the seller (not Amazon) that I had to mail them back at my expense which ended up costing over $17.  They had sent them in a USPS mailing envelope so I had to buy a box and packing tape as well.  Since these were purchased for a hiking trip in less than 2 weeks I found a local hiking store where there was not only a sale on waterproof boots (I got 7.5 Merrells brown Siren WTPF for $104!) but was informed by their shoe experts that the Merrell Moab runs bigger both in width and length than the norm.  So lesson learned: always check the seller's exchange/return policy and never, ever buy footwear online.  3/26/13 addendum: as always, Amazon comes through.  They credited my account the amount paid for return postage which they didn't have to do.  I just hope the seller comes through w/my $114 credit for the returned boots.