What is an "air guide"?

In my Hayness manual I see that an "air guide" should be present on the rear swing-arm.
This has probably been taken off by the previous owner of my VFR, since mine doesn't have one.
What is the function of this device and do I need it?

 

If you really want one they are still available from mother Honda new, or you can grab a used one off eBay. 40515-MBG-000

 

I have both.

The Haynes is great for the less experienced, back yard grease monkey. For relatively simple and routine matters, I prefer the Hanes. The illustrations and images are far superior to the owner's manual. But if you are going to get into a more complex service or repair, then I use the Owner's Manual. I find I use the Haynes more often.

I really must take the plunge and pay an outrageous price for an Owner's Manual for my Africa Twin one of these welfare cheque days.

 

Perhaps the cooling could have avoided the rear caliper meltdown, that the previous owner allowed to happen...

 

The practical purpose of that is to help avoid getting clothing, etc caught in the chain and sprocket

 

A-hah! So actually it is a (loose) hair guide!

 

Like a bench grinder might have? (my buddy Scot with the hair and Bones, one of the mechanics).