To use you thread a loop of webbing through the slot and insert peg in loop to prevent the loop slipping back through the slot. You then stretch the webbing by levering the tool against the side of the chair frame.
Walthamstow Tool Library
https://frpuk.org/community-work/tools/
2a Priory Courthttps://frpuk.org/community-work/tools/
London, E17 5LS
United Kingdom
07933710644