Drive shaft velocity measure, measures epicyclic angular differences when using a universal joint at different angles. Used condition, still moves smoothly. Teaching aid in Mechanical Engineering. Length when straight: 38cm. Each foot : 19cm x 7.5cm. Diameter of wheel approximately 10.5cm. Please see photographs for more information regarding design and condition. We always have new stock so keep checking our shop for new listings. Viewing our items is possible (by appointment only). Alternatively you are more than welcome to collect the item. If you are not happy with your item please return in the original packaging and with all tags attached within 30 days.