"prohibited firearm"
(b) a firearm that is adapted from a rifle or shotgun, whether by sawing, cutting or any other alteration, and that, as so adapted,
(i) is less than 660 mm in length, or
(ii) is 660 mm or greater in length and has a barrel less than 457 mm in length
"restricted firearm"
(b) a firearm that
(i) is not a prohibited firearm,
(ii) has a barrel less than 470 mm in length, and
(iii) is capable of discharging centre-fire ammunition in a semi-automatic manner,
(c) a firearm that is designed or adapted to be fired when reduced to a length of less than 660 mm by folding, telescoping or otherwise, or
(d) a firearm of any other kind that is prescribed to be a restricted firearm;
As far as I can tell the Remington 870 with 18.5" barrel and top-folding stock in the picture is well over 26" (660mm) and classified as Non-Restricted by our silly system.