For the DC14 check your manual or download - this belt does fit but you need expert dismantle skills and some very sneaky lock screwdrivers to change the belt. It appears there are 2 types of DC14's because the original intructions which come with the belt (If the seller ships you an original pack it comes with FULL instructions) but they are a waste of time on the DC14, our design was completely different to the instruction !!??. When I took it eventually to a Dyson dealer it was £30 to change the belt (of course he did not charge me for belts but had a nice smile about it..) but it takes 1 hour to remove and change (he told me they do this on purpose !).
So be caresfull. On top of that the original seller (Spare-2-Go shipped a 3rd party pack) - they did replace them when I complained but I wonder if they would have if I kept quiet. Original Spares come in a Silver DYSON box with instructions, not loose packed. The orignals are stamped DYSON on the belt in white writting (like the picture) and they have an additional emmmeded thread in the rubber to prevent shreading, 3rd party products loose packed - do not.