These are the same strings that Rogue uses in their prepackaged retail sets. What's the difference? We package 12 strings of the same gauge in airtight vinyl bags with a package of silica gel to protect against unwanted moisture so they last longer than typical string sets. We also pack these bulk strings in big, loose coils to avoid compressing or stretching the windings, so they sound better than tightly coiled strings. To order replacement strings, simply choose the type and gauge strings you need from the chart below, and order by item number and gauge. You will receive one bag with 12 strings for each gauge you order. All Rogue P13 Bulk 12 Pack sets use Plain Steel for the first 2 treble strings (E and B). For electric sets, specify either Nickel or Stainless Steel for the wrapped strings. Acoustic sets available in Phosphor Bronze.