Now that you've selected a harness for your pet, you'll want to know how to fit it properly. Adjust the harness to what you believe to be the appropriate size for your ferret, then try putting it on your ferret. This is not a simple task - ferrets are wiggly animals and if they have never used a harness before, they will be trying to sniff the harness and examine it while you are putting it on them. Sparkle will assist us by demonstrating different harness adjustments.
If the snaps are difficult to do up, then the harness it too tight. Put the ferret down and loosen it slightly.
If you have any more than, say, a pinky width of extra space, then the harness is too big. Put the ferret down and make it smaller.
Ideally, the harness should be snug with approximately a pinky of leeway to allow the ferret to breathe. A harness that fits these parameters fits nicely.
*** Due to how they are built, ferrets will always be able to slip their harnesses. A properly fitted harness does not ensure that the ferret will not be able to slip away, it simply means that they will need to put more effort into it, giving you more time to notice and pick your pet up. DO NOT attempt to tighten the harness to prevent this - doing so will strangle your pet.
Now your ferret is ready for the great outdoors, right? WRONG! There is still one more step that needs to be taken before you and your pet can head out for an adventure.