I spent some time on the Mossberg website and I'm pretty sure the barrel offered is for an 835 - the magazine loop appears to match the style of the 835 while the bbls on the 535 have the same loop / cap arrangement of the 500. The seller doesn't seem interested - sure hope no one gets messed up with the wrong barrel but I won't be buying.
I did email Mossberg but no answer so far.
Rats, I have been keeping an eye out for a 24 inch bbl with screw in chokes to set up for turkey hunting - for less than what Midway wants.
Thanks for the help folks.