Floor spring for double action doors, with hydraulic fully controlled closing from approx. 130°; including cement box and removeable spindle insert. The DORMA BTS 84 is a double action floor spring which has been specially developed for the aluminium and toughened glass door industries. This unit is intended to complement our internationally acclaimed RTS concealed overhead door closer by giving the shopfitting industry the option of a DORMA quality floor spring designed for their particular purpose.