whats with these tail ends

[EXC-Rider]

have any one seen these tailend on some bikes , looks kinda cool but have no idea what these are called or what, i think its most street fighter bikes have them

https://thekneeslider.com/images/bmwstreetfighter.jpg
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owned bikes: DR50, Thumpsta 110 , Honda CR85, Speedfight 100, Yamaha XT125X, Honda CRF450, Honda Hornet '07
current bikes: KTM EXC525 AKA the wheelie machine
A friend in need is a friend indeed but a friend with weed is better!

[mad4it028]

hospital bikes? cant say ive seen a red cross on any other bikes
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved