Tungsten guide rod is a full length guide rod made of Tungsten which is heavier than steel. Extended dust cover means the portion of the frame extending in front of the trigger guard is lengthened out to be flush with the end of the slide (Les Baer Monolith has and extended dust cover). Both of these items are used to add weight to the muzzle end of the pistol to reduce muzzle flip and felt recoil.