The job is anti vandal roller bars fitted to our flat roof

Use metal bird spikes it’s cheaper

Rollers are great, as would look not that aggressive compared to spikes. And could be as well painted to match your building colours for much pleasing aesthetics.

The spikes and bars do the same job ,but definitely the bars if the roof can be seen by the public ,the spikes I think actually attract the unwanted as it looks like you have something valuable inside, or hiding something ,more costly but worth every penny .

Do it yourself