i dont run one as i like to check the condition of teh belt etc

but cossie cambelt covers are a pain in teh arse

mine always rubbed on teh bottom pulley and took it off just incase it did decide to break through and a bit of plastic got stuck in teh teeth of the pulley

i have one now which is in half just to cover up the rusty pulleys

as i couldnt get it to fit correct at th bottom due to the pulleys

plus its going to be quite rare to get a stone in there anyhow unless you hit a gravel patch on a track day