AO2's Knucklebone is the original hardbody knuckle roller, make no mistake. This is a simple skill toy that is manipulated with the fingers of one or both hands to perform tricks and patterns, or simply to pass the time. It is very discrete (unless dropped) and can be played in very restricted spaces, and in contexts where other showier skill toys may not be appropriate. 

The kbone is very appealing, not only for its elegant form and ergonomic design, but also, for the range of play styles that it enables. The rounded lines are perfect for spinning, flipping, and passing it between the fingers. It can be manipulated very casually and quietly like a worry stone, or can be used to perform a surprising array of freestyle flows, technical tricks, isolations, and even aerials. There are a handful of tutorials already available online at the AO2 YouTube channel, and we’ll be publishing more in the coming weeks to help get folks started. 

The delrin version is light and smooth feeling. Unlike metal and other plastics, delrin has a warm feeling, almost reminiscent of wood. It is also very durable, and stubbornly resists dings and breakage. It will scratch, but because it is relatively light, it tends not to take (or inflict) heavy damage when it is dropped. 

The weight and smoothness of the toy are variables that affect play, and each material seems to be suited to different kinds of tricks. The delrin version is conducive to quiet manipulation and two-play including transfers, twiddling between fingers, and two-handed rolls. 

Kbone L and XL

The Large and XL versions are well suited to players with bigger than average hands, and for those who want a little bit of extra weight and momentum to swing through tricks like sonics and aerials. Specs are below: 

• Kbone original in delrin:  6cm long and 14g
• Kbone L in delrin: 6.75cm long and 20g
• Kbone XL in delrin: 7.5cm long and 29g

While the sizes and weights don't sound like much, the feel of the L and XL versions is very different from the original. They are more suited to momentum tricks, and do provide for more stability, but for those with averaged hands, they may feel somewhat awkward at first. If you're used to the original, then the XL "jumbone" is going to look and feel comically large when you first handle it. As with the various materials, the different sizes all have their merits. 

The weight and hard material mean it will make a loud noise when it is dropped on hard surfaces, and has the potential to break things in its path. Be careful with it.

Note from the designer: I developed the original knucklebone circa 1989 when I was a kid in school. The crude original version was made from some kind of polymer clay (see photo). The new version is better suited to bigger hands, and has been designed for smoother flow and better trick potential.  

Warnings: Metal versions are heavy and solid--can break things or hurt things if dropped. It is recommended that you play over carpet, couch, or the like, or outside. Delrin versions look almost tasty, so keep them away from young kids, and don't let anyone try to ingest them.