Massive Attack 5-pack
The Particle Zoo
Whoa! Heavy guys! Contains a Higgs Boson, Z Boson, W Boson, Dark Matter, and Top Quark. The shipping might kill you on this one, but those exotic massive particles are so worth it. All filled with gravel.
Approximately 5 lb (2.3 kg).
For ages 5 and up as it contains glued-on/small parts.
The Massive Attack 5-pack is available in a lightweight shipping saver version which is especially nice if you live outside the U.S. All 5 plushes will be filled with lightweight stuffing. Of course you won't get the full effect of their weightiness, but they will be the same in every other way.