Check The Rule Book.

Last time I looked it was .012" for 1/2A and .018" for Speed Limit, Slow & Fast, all stranded steel.

But now that the "book" is on software it can change ANY time.  I guess you would need an I-Pad if you wanted to argue a rule.

What Larry said! Spiderwire is not Spectra do not use it. It has different properties than Spectra line. Page 5 of the rulebook outline the use of Spectra line. https://www.modelaircraft.org/files/2015-2016CLGeneral.pdf

Current AMA rules allow for these lines in combat and have for several years now.  Rules call for the same diameter & same pull test as braided metallic lines.  The rules change to allow this followed the standard AMA 2 yr cycle.  As such, per contest procedures, they are legal unless the CD puts it in his contest announcement that synthetic lines are specifically prohibited.

 just ordered the lines from ebay, do u use eyelets or just make loop

It's pretty important to stick with name brands and either Spectra or Dyneema(Europe).  It's also called  ultra high molecular weight gel spun polyethylene.  It's a pretty fussy process because the temperature of the plastic is highly critical.  The polyethylene is extruded through a very small die and stretched rapidly while it cools.  The process makes the long chains of the polyethylene(high molecular weight means long, unbranched molecules, some 400,000 atoms long) line up very tightly packed and all forced very close to each other.  The individual strands are gathered into bundles of several hundred fibers and the bundles are braided into the line.  The result is a cable as strong and resistant to stretching as high strength steel, but only 1/7th the weight.  Depending on how it's braided in may be slightly draggier than steel lines.  On the plus side, besides being easy to tie to an exact length it won't tangle itself up, kink, or fatigue and break from vibration, or get damaged by a Big Foot tripping over your lines.

Since it's made entirely of polyethylene which melts at 275 F the line shouldn't be exposed to temperatures much over 150degF, certainly not high than 175-212 degrees.  When the strand gets too hot the molecules can lose their straight line orientation and get more loosely packed loosing most of their strength.  For similar reasons it's easy to make mistakes in manufacturing that give the same result- a stretchy, low strength strand that's useless for flying models.  You won't know a low cost knock off will work until you get it home and test it with a pull tester.  If a 60 ft. line stretches more than 1.75-2in with a 25lb. pull test it's too stretchy and is not the right material.

Fly until you've had so much fun you fall over,

Phil C

They sure make it look easy.   How do you get both lines the length you want and the same?

Just a little note about Spider Wire lines. Several years ago Andy and I were flying our kites. Yall seen these little haul ass kites before (i'll try to do an attachment) Anyway, Andy got his spider wire lines all tangled up in some weeds and finally just trashed them. He had a set of steel 1/2A lines with him so he just put them on. He flew about 15 seconds and it broke both steel lines! We were quite surprised. The kites do pull pretty hard, but we sure didnt expect that. Later I was gonna get cute and fly under a soccer goal post and hit the post with the line and do a 90* turn. As soon as my Spider wire touched the goal post both lines broke. Didnt expect that either. Andy and I have flow combat many times with spider wire on the kites and wrapped up and never broke any. Looks like both spider and steel have their weakness, just pick which one works for you.