I’ve been using Cobalts since last fall. Loved the aggressive growly tone. Two sets No problems. With the third set they rusted out after just 3 weeks! I quickly ordered another set and contacted EB who sent me two free sets. Changed them this past Wednesday night. After just 72hrs the D and G strings are starting to show signs of rust!! I can’t believe this is happening again! I keep my studio at a steady 71-74* and 60% humidity. I’m careful to wipe my strings down after each practice. (Every night). EB definitely has a QC issue with these strings. After reading all the random posts about them and going through two sets without problems I thought I was free and clear. Not anymore. I’ve decided to go back to DRs. Had a new set of LoRiders laying around and just put them on. Problem solved. Too bad.