One of the greatest advancements in plastic gears has been K2's no weld line technology.

A weld line is the interface in an injection molded gear were two flow fronts meet.  These weld lines usually occur between two gates (points where plastic is injected into the gear during manufacturing). 

A competitor's Nylatron gear on the right has 6 pronounced weld lines caused by six gates.  K2's much improved gear made of the same material is on the left.  See the difference for yourself. 

A weld line is the weak link in a gear.  The material strength at the weld line may be 10-50% the strength outside the weld line!  This means you can not rely on material data sheets for strength calculations without factoring in the effect of weld lines.  You can also achieve 2-3 levels of accuracy higher without weld lines!

K2 has unlocked the secret to molding plastic gears, pulleys and bushings without these dreaded weld lines and with no secondary machining.   See how you can now buy stronger more accurate gears at a fraction of the cost of the competition!