... different sizs , materials, standards and finishes . square head boltstandard : JIS , DIN . AISI, GB .material : carbon steel , stainless steel ... A193 GR.B8, B8Mfinish:plain , black oxide , blue zinc ,yellow zinc , black zinc , nickel and so on.We are professional manufacturer and ... be brass , aluminum , carbon steel , alloy steel , stainless steel , zinc , and so on . Our strong R&D and QC department ...