Most of the best Graduated Neutral Density filters (aka ND grads or GND filters) are of the slot-in variety, but these circular ND grads screw directly into your lens's filter thread without the need for additional holders. But what they gain in portability and convenience, they lose in flexibility; the graduated transition area is fixed at the center of the filter.
There's a choice of two filter strengths, offering a three- or four-stop difference between the clear portion and darkest area of the filter. There's no hard graduation on offer, so the transition from light to dark on offer here is better suited to more undulating horizons, such as rolling hills, buildings, or mountains, rather than seascapes.
