Comment on PurpleScape by GoranDA
glad to be compare to these guys, thx 
the filter kit is a cokin z_pro filter holder, it allows you to use rectangle filters, very useful for the gradient neutral density filters, as you can fit the gradient to the horizon line. with circular gradient neutral density the gradient is stuck to the middle. Moreover, this kind of holder can be fit on every lens with different adapter rings. the advantage of the "Z" holder compare to the regular "P" holder is that it uses larger filters (4 inches vs 3inches) and then can be used on very wide angle lens without inducing vignetting
the filter kit is a cokin z_pro filter holder, it allows you to use rectangle filters, very useful for the gradient neutral density filters, as you can fit the gradient to the horizon line. with circular gradient neutral density the gradient is stuck to the middle. Moreover, this kind of holder can be fit on every lens with different adapter rings. the advantage of the "Z" holder compare to the regular "P" holder is that it uses larger filters (4 inches vs 3inches) and then can be used on very wide angle lens without inducing vignetting
