Special order 105mm screw-in glass polarising filter which saturates colours and deepens blue skies, and reduces reflections off water and glass. The Linear Polariser cannot be used with autofocus cameras, and some manual focus cameras which use beam splitters in their metering systems. The advantage of a 105mm round polariser over the square 100mm type produced by Lee is that it can be used with the standard Foundation Kit holder and graduated filters. To use grads with the square type the Professional Kit is required, in order to allow independent rotation of both polariser and grad. As a result the greater extension of the Pro Kit in front of the lens severely limits use with wide angle lenses. The 105mm polariser fits to the front of the holder by means of the 105mm Polariser Adaptor Ring (extra).