These are genuine Westwood Non-Webbed Sweeper Bristles (set of 54) p/n 14898101. They fit the Tractor D1850, Tractor A2050, Tractor C series MK1, MK2 & MK3 & many other machines. 54 bristles are required for a Standard 36” Collector. Length: 145mm If you are unsure whether this is the correct part for your machine, please fill out our online parts enquiry form here. The technical department will then respond to confirm whether or not it is the correct part for your machine.