which one is stronger？
 

I only know that Blue Titanium Turnbuckle 3×42mm (42120) is lighter than Hard Turnbuckle Shaft (53942), and I want to know which one is stronger？

Thank you very much

you would find it nearly impossible to find anything stronger than titanium...

Weight vs. strength ratio that is :) A 3mm turnbuckle from steel will be stronger than a titanium one, but steel weighs considerably more.

If the 'Hard' turnbuckle shafts are steel, they will be stronger. Just remember that steel weighs about 70% more than titanium, and that you may not need the extra strength they provide. You'll probably bust your adjusters or have them pop off before the titanium turnbuckles start to bend :p