Teng Tools Rigger Jigger - the official trade marked brand.
A rigger jigger is 10mm at one end and 13mm at the other.
An essential for every rower as they undo every nut in a European boat - 10mm for the riggers and 13mm for the top nuts. Compact length which is handy for your bumbag or pocket and minimises the risk of overtightening. But watch out as they go missing very easily and are always being "borrowed"!
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