VHBC DZR Hose Union Bibchecks otherwise known as a Hose Union with double check valve. Manufactured to BS6282 Two sizes available in this section 1/2" Bibtap with double check valve 3/4" Bibtap with double check valve - IMPORTANT NOTE, MOST PLUMBING PRODUCTS ARE STATED AS BSP IMPERIAL THREAD MEASUREMENT WHICH MEANS THAT ACTUAL DIAMETER OF THE THREAD SIZE IS APPROXIMATELY 1/4 INCH LARGER THAN THAT STATED IN BSP TERMS. FOR EXAMPLE THIS 3/4 INCH BSP THREAD ACTUALLY MEASURES APPROXIMATELY 1 INCH IN DIAMETER