Fixings should be tight against the tread and any movement generally indicates faulty, loose or worn fixings which should be replaced immediately with approved fixings.
Manufactured from high impact ABS, tested to withstand 400kg. However, loose fittings change the stresses on the tread and significantly reduce the weight bearing limit on the tread.
Plastica Tread Dimensions
End to end length - 47cm
Length between ladder tube cut outs - 43.5cm
Width - 8cm
Depth - 5.5cm (at each end)
Certikin Tread Dimensions
End to end length - 47.5cm
Length between ladder tube cut outs - 44.5cm
Width - 8.3cm
Depth - 3cm (at each end)
To identify which step tread it is that you want, the Plastica step tread has wavy lines and the Certikin step tread has straight lines with triangles on it.