Most important part is to get a clear/protection filter.
I thought 60D is weather sealed?
Otherwise, why pay anything for a glorified plastic bag as shown in your photo sample.
I'd just use a good thick transparent ziploc bag, cut a hole in it for the lens.
Put the camera in and seal the ziploc + tape up.
Then tape the cut hole where the lens protrudes.
Best thing about it is that in the case that the dust enters the cover, you can change to a brand new one
If your lens is not weather sealed, its still a risky proposition. Armour column moving in Ex. Wallaby is super dusty.
The piston action of the zoom and/or AF will suck in fine dust if its not WS.
In such cases, I'd suggest 'bagging' the lens and not using the zoom if condition is suspect.