... EN74/BS1139 :Type: Forged Single coupler Single coupler Scaffolding Single coupler Steel Single couplerSize: Single coupler Single Coupler ... , 19mm, 21mm, 22mm, 23mmCertificationISO9001:2000, CE, SGSBritish Type Scaffolding Single Coupler with EN74/BS1139 :1) Material: Q235,2) ... retainer, toe board fixing, ladder bracket and so on. Double coupler 1.join two scaffolding tubes having outside diameter of ...