After my needle felt flooring and chair rollers had ruined each other, both had to be renewed: a castor chair resistant and antistatic (because of Computerbauerei) flooring and new chair castors. Both a great job, it's fun to roll the chair. It should be noted: - Soft ground or hard soil - Better 65 than 50 mm diameter - Crucial to the correct pin diameter. Castors are available with 10 or 11 mm, with the old I measured 10.5 mm, 11 betellt, I would if necessary reamed carefully to the chair. But was not necessary. I am really very well pleased
