3M Skull Screws Probed Test Plugs are a specially probed version of the standard plug. 3M Skull Screws Probed Test Plugs are a specially probed version of the standard plug. This product works with the E A Rfit Validation System and allows you to conduct an earplug fit test for the P1300 and P1301 earplugs. 7000128264 - 10093045937131
