Those started out over here;
http://www.aerographix.biz/fuel_tanks.htm

Yep, cool tanks & the clunk is easily seen!

For their shorter 8 ounce tanks (ONLY), a few mods are needed (their clunk is too light & std tygon isn't flexible enough in such a short tank).

The ceramic clunk/filter I prefer is a Poulan 530095646, and weighs 0.4 ounces.

More flexible fuel line;
Oregon [part #07-266] .094" I.D. x .203" O.D. [wall thickness=.050"]

{Std Tygon 1/8" I.D. x 1/4" O.D. [wall thickness=.060] }

ONLY required in their shorter 8 ounce tanks.

I always use zip-ties and never ever had any leaks!