MGF sill protection covers sold as a pair, left and right, made in 304 Brushed satin Stainless Steel.  Designed and manufactured in the United Kingdom by Mike Satur.
These have been designed to allow air flow behind the panel so there is no build up of damp which can accelerate rust.
They are held on with 4 SS screws in the lower flange and two  ss endcaps a strip of high bond tape is supplied which is applied along the top edge, once fitted it is invisable.
These are not meant to cover up rusty structurally weak sills but to prevent damage from stones and further rusting. The end caps protect the arch edges from stone abrasion damage.
The MGF sills can suffer damage and are often neglected it is advised that the sills are cleaned of any surface rust and damage to the jacking points painted and rustproofed before fitting, if necessary replace rusty sills with my sill replacement panels. 
The stainless sills will  reinstate that sharp line to the sill edge and enhance the overall appearance negating the need for a black underseal line which looks unsightly.
Because of the length for shipping the cost  for shipping is a bit more than a regular size parcel.