... 21mm, 22mm, 23mmCertificationISO9001:2000, CE, SGSBritish Type Scaffolding Single Coupler with EN74/BS1139 :1) Material: Q235,2) Processing method: drop ... as spigot support, deck retainer, toe board fixing, ladder bracket and so on. Double coupler 1.join two scaffolding tubes ... parts on the assmbly systems of system scaffoldings .The vertical pole,the ledger,the corss braces,the tri-brackets,planks ...