I make all my own. I use Berkley nylon coated stranded leader wire. You can get it all the way from 20 # to over 100# breaking strength. Most planes get by nicely with 30 to 60# line. They also sell the crimping ferules which you can easily crimp with a set of dikes or other crimping tool. I never attach directly to the servo, I always make a pulley about a.5 to 2.5 inches in diameter and mount it withing about 4 inches of the servo. The line to the moveable surfaces then goes around this pulley and back. You need to anchor it to the pulley so that it doesn't slip. I then use a very stiff short arm from the servo to the pully using ball link hardware. Do not, repead

I make all my own. I use Berkley nylon coated stranded leader wire. You can get it all the way from 20 # to over 100# breaking strength. Most planes get by nicely with 30 to 60# line. They also sell the crimping ferules which you can easily crimp with a set of dikes or other crimping tool. I never attach directly to the servo, I always make a pulley about a.5 to 2.5 inches in diameter and mount it withing about 4 inches of the servo. The line to the moveable surfaces then goes around this pulley and back. You need to anchor it to the pulley so that it doesn't slip. I then use a very stiff short arm from the servo to the pulley using ball link hardware. Do not, repeat, DO NOT, make the lines real tight, just snug enough so that they do not slip off the pulley. By having a pulley (not a bellcrank) in this position, you can make small adjustments about neutral without fouling up the throw geometry. You can move the attachment point at the moveable surface in or out without having to worry about geometry as the pulley always takes in as much line as it pays out. Make sure that the attachment points on the horns at the moveable surface are right above and below the hinge line or just slightly aft and that both top and bottom are equal distances from the hinge line. If they are forward, the lines tighten up when you move away from neutral. If they are aft, the line not being pulled will sag a slight bit but this does not hurt the control response nor load the servo as a tight line will.