Handles for needles suitable for pelvic floor surgical procedures are described. Other aspects are described and claimed. The radially outermost of said first and second members moves to a wall of the vessel relative to stress and displace material present between the mixing apparatus and the wall of the vessel. When a relay coil is not excited, the first and second moving pieces are resiliently urged into contact with a back-stop plate, displaced from the first and second fixed contact elements.