What is an existing wall anchor? by Jason Miller · Published April 29, 2009 · Updated November 30, 2016 A flat head combo drive sleeve anchor available in 3/8″ diameters 4″, 5″ and 6″. Manufactured in zinc plated steel and stainless steel. Packaged in small box quantities and Bucket of Bolts! Also known as ThunderBolt, DynaBolt, and LokBolt. Flat Head Sleeve Anchor Bucket Of Bolts!