Specialty Items Leave a Comment / Uncategorized / By Derkia-Bolt Derkia supplies a wide range of concrete reinforcing, embedment & construction materials and fasteners.In addition to regular & weldable G30.21 400 rebar we can provide; epoxy coated, stainless steel, MMFX & GFRP bar as well.Some of the other products provided include couplers, coupling nuts, anchor bolt sleeves and lifting hooks (manufactured in house).