one of the best inventions in modern times IMO
for all those new beekeepers ....."back in the old days" if you wanted to move a hive a triangular plate(one on each side) or a large staple(one on each corner) was used to screw or nail the floor to the brood chamber then the brood box to the super and then to possibly another super then the travelling screen was screwed down to the super(no crown board as it helped with ventilation, no OMF either) a long loborious job considering there was no such thing as a cordless drill. Then the whole process had to be reversed when the honey a was taken off.
a spanset is so quick and easy, although initially its easier with two.
one thing you have to be careful with is over tightening, if you have an OMF without the tray in the bottom it can tend to pull the sides in of the floor.Or if its put on when the hive is very wet, if moved after some dry weather the strap can be a bit loose