I recently put one on my pleasure way- if it had a cover, the P/O probably got in the trees as the tv antenna was damaged.
Mine was under $20 (amazon pricing is 'dynamic' it shows higher as I write)
bugs I don;t worry about- it does have a screen
the low pressure zone caused by the wind passing under the cap over the vent pipe does draw fumes from the tank- a vast improvement.
without, when driving positive pressure can be made in your tank, pushing fumes into the RV
The mounting allows for a few options, I didn;t use the base plate surround, but attached directly to my stub with a little silicone and drilled a hole for a set-screw.
my review: 5 star