Adding a tail tidy to your KTM Duke 125 can be a worthwhile mod. Although it's not going to do anything to improve your bike's performance it will do exactly what is says on the tin and 'tidy' up the appearance of the back of your bike.
KTM Duke 125 Tail Tidy For Sale
Tail tidies are usually straightforward to fit yourself at home and in most cases it's unlikely that you will need a mechanic to fit it. Most tail tidies from companies such as R&G or Yoshimura will come with comprehensive fitting instructions making installation a breeze. Check that the tail tidy that you buy will allow you to use the original turn signal indicators, or you may prefer to replace these with mini indicators which are widely available.