Samson Mfg's reengineered version of the original AC-556 style gas block front sight with integrated sling attachment point. 2008 or later in Black or Stainless are compatible with Mini-14A(R) rifles with a factory flanged .625"" diameter barrel manufactured in 2008 or later, with a serial number prefix of 508 or higher. Additionally, Mini ThirtyA(R) rifles with the older factory straight pencil .625"" diameter barrel and the new factory flanged .625"" diameter barrel will be compatible. 2007 or earlier in Black or Stainless are compatible with Mini-14A(R) rifles with a factory straight pencil .562"" diameter barrel manufactured i Mfg: Samson Manufacturing Corp