Basics Jumbo needles were created in lightweight and strong birch wood. The handsome natural birch color makes them as easy on the eye as they are on the hand - especially when working with today's thick and chunky yarns. The lightness of the wood allows us to produce them in sizes up to US 50 (25.0mm). They are ideal for knitting projects such as blankets, rugs and large-scale garments and coverings of all types. The largest sizes can also be used as decorative items in homes, schools or studios.