Carlos here is a little tutorial on the Tetra at Darol Cadys site He has the Tetras up to Six ounce which is what I use. The larger sizes are at Central hobbies. To properly fill you will need the Jatt Tanker (a large syringe) that allows all air to vacated before the fuel is pushed into the bladder. Darrol Cady also has the Jett tankers and i will find the link for Dub Jett in a moment.
http://www.darrolcady.com/Tettra_Tan...tra_tanks.html
Here is Dub,s site where you will also find tutorials and a variety of his tanks for very slim installations. One of which is called the CG tank (this is because it is very slim) that will slide into a very small nacelle. I had great luck in running bubbless tanks as far back as eight inchs from the firewall in a variety of installations.
http://www.jettengineering.com/
John