I’m not a great fan of tail tidies even though I avoid riding in the wet. For those who can’t resist the racer looks of a bike fitted with a tail tidy there are several options for the Duke 4.
KTM offer a PowerParts item (76008915044) at a UK online price of £155.
R&G Racing offer a smaller, neater tidy, illustrated below at an online price of £75.
The neatest and best looking of all, in my opinion, is the tidy made by EvoTech at an online price of £95.