| DRAINAGE COUPLINGS | ALIAXIS UK |
| CLARK DRAIN LTD |
| FERNCO LTD |
| GEBERIT SALES LTD PIPING SYSTEMS |
| HEPWORTH CLAY & TERRACOTTA |
| OSMA |
| PAM BUILDING |
| POLYPIPE BUILDING PRODUCTS |
| DRAINAGE COUPLINGS AGREMENT CERTIFICATE HOLDERS | OSMA |
| POLYPIPE BUILDING PRODUCTS |
| DRAINAGE COUPLINGS BS EN 10088-2:1995 | FERNCO LTD |
| DRAINAGE COUPLINGS BS EN 1401 | FERNCO LTD |
| DRAINAGE COUPLINGS BS EN 295-4:2013 | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| OSMA |
| DRAINAGE COUPLINGS BS EN 295-4:2013 Kitemarked CE Marked | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| OSMA |
| DRAINAGE COUPLINGS BS EN 681-1:1996 | FERNCO LTD |
| DRAINAGE COUPLINGS Cast Iron | ALUMASC WATER MANAGEMENT SOLUTIONS |
| FERNCO LTD |
| OSMA |
| PAM BUILDING |
| DRAINAGE COUPLINGS Cast Iron BS EN 877 CE Marked | ALUMASC WATER MANAGEMENT SOLUTIONS |
| PAM BUILDING |
| DRAINAGE COUPLINGS Cast Iron Push-Fit | PAM BUILDING |
| DRAINAGE COUPLINGS Chemical Resistant | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| DRAINAGE COUPLINGS Clay Pipe | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| DRAINAGE COUPLINGS Ductile Iron | PAM BUILDING |
| DRAINAGE COUPLINGS EPDM/SBR Rubber | FERNCO LTD |
| DRAINAGE COUPLINGS Flexible: | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| OSMA |
| POLYPIPE BUILDING PRODUCTS |
| DRAINAGE COUPLINGS Flexible: Pipe Crack Repair | FERNCO LTD |
| DRAINAGE COUPLINGS Flexible: WIS 4-41-01 Kitemarked | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| DRAINAGE COUPLINGS Flexible: WIS 4-41-01 Shear Banded Couplings | FERNCO LTD |
| HEPWORTH CLAY & TERRACOTTA |
| DRAINAGE COUPLINGS Precast Concrete | FERNCO LTD |
| DRAINAGE COUPLINGS PVC Fittings | CLARK DRAIN LTD |
| POLYPIPE BUILDING PRODUCTS |
| DRAINAGE COUPLINGS Variable Bend | FERNCO LTD |
