F.A.S.T. 401k
Manufacturer YoYoFactory
Release date 2005
Shape Butterfly
Color Various
Weight 68 grams
Dimensions Diameter: 56mm
Width: 42mm
Material Aluminum
Bearing size Size A
Response system F.A.S.T. 400 Series shuttles

The F.A.S.T. 401k by YoYoFactory, is a yo-yo released in 2005. The body is machined from high-grade aluminum. The yo-yo response system is the F.A.S.T. 400 Series shuttles (in this case, the "A" in the acronym stands for Adjustable), which consists of two knobs on the outer hubs and plastic starburst pads or "shuttles" as they are referred to. There are one hundred and eighty different response settings, ninety for each side of the yo-yo, .001 of an inch apart (the thickness of a human hair). The shuttles can be set in a flush or recessed position on the inside surface of the yo-yo by turning the knobs. It also comes with two extra shuttles for when the ones on the yo-yo wear out from extensive use. Because the yo-yo uses an A-bearing, it can use small bearing response pads, giving the user a choice to use nothing but pads, or a combination of one pad and one shuttle. This made the 401k a flexible design, and a real innovation as the first yo-yo to feature a truly adjustable response system.

YoYoFactory had also released an "espionage edition" of the 401k in 2006. At one point, YoYoFactory had also released a Yuuki Spencer edition, which is blue, and comes with black/red shuttles. There was also a Team edition of the yo-yo, which comes in different color combinations and had the Team YoYoFactory logo on the rims, along with rubber shuttles and a velour finish.

At one point in 2005, YoYoFactory released an upgrade kit for the F.A.S.T. 401k, which included the rubber shuttles and a high-quality Dorothy bearing.

Sometime in 2006, YoYoFactory discontinued the 401k.


  • The 401k is the second yo-yo in the F.A.S.T. series to be made of aluminum, the first being the very limited F.A.S.T. 301, of which 121 pieces were made.
  • F.A.S.T. 401k yo-yos were also given out as prizes in the F.A.S.T. Challenge in Singapore.
  • It is also the first F.A.S.T. series yo-yo to not utilize the F.A.S.T. 201's response system.


External Links

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.