Derek - I used a Fiamma-Zip model for a couple of years - you can buy the side and front panels separately if you want a waterproof unit - I would not buy the non-zip Fiamma unless you want a canopy only. Slide the unit into the awning rail[you have to unroll the canopy to do this]. Slide it to your chosen position,roll it up into the cover,fasten with 3 velcro tapes provided and zip in. There are small adjustable screws provided that slide into the awning rail from each end up to the Fiamma unit - tighten these and the unit stays in the same position.I liked the idea of these as you can use them as a canopy only in the summer or attach sides or front and sides to make a more stable unit. You can buy lots of Fiamma parts for it.
Unfortunately the Caravan Club do not recommend these as they say the weight high-up on the awning rail could make the caravan unstable while on the move - I personally had no problems.Summarising i did enjoy using it,however i now have a large porch-awning which is just as easy to erect as has a stronger pole connection system.You pays your money and takes your choice - Fiamma porch-canopies start from around