The Krobahn Monobloc Tap Spanners (KB-MBTS0004) is a 4-piece set of double-ended box spanners designed for installing and removing monobloc tap back nuts in confined spaces. The set includes a tommy bar for leverage and is available from several online retailers. 
Product Details
Model Number: KB-MBTS0004
Material: Manufactured from steel tube with a galvanised finish
Length: 185mm
Spanner Sizes: 8mm/9mm, 9mm/11mm, 10mm/11mm, and 12mm/13mm
Contents: 4 double-ended tube spanners and 1 tommy bar
Design: Double-ended box spanner design for added convenience and access to restricted areas.