Tubing which had a yield strength higher than standard. Yield strength indicates the stress required to permanently deform the material. Standard supply-house tubing may have a 30,000psi or 35,000psi minimum yield strength, but most* Powerbrace lockrods are made using a minimum 55,000psi yield strength tubing. Additionally, Powerbrace tubing is manufactured with demanding diameter and straightness tolerances that far exceed standard supply-house tubing. The specification for stainless steel lockrods is 30,000 min. yield.