An adjustable spanner or adjustable wrench is a spanner with a "jaw" of adjustable width, allowing it to be used with different sizes of fastener head (nut, bolt, etc.) rather than just one fastener, as with a conventional fixed spanner. An adjustable spanner may also be called a shifting spanner, shifting adjustable, shifter, fit-all, crescent wrench (incorrect usage - see Famous brands section), adjustable angle-head wrench or Bahco (see below).
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