I recommend clear (for external use) selastic.  When it rains no problems with the external use one.

Mine fell off, the local bike shop (Phil's Garage in Albury) found one for me & put it on during a service. It is a slghtly different shape but I am not too concerned.

That reminds me I must glue them on, I wonder if blue tack would hold trhem in place & ro do they need to come off for some reason.

 Bluetack????????? FFS!!!