Formatt-Hitech 100x100mm (4x4") ProStop IRND Long Exposure Kit - Joel Tjintjelaar Signature Edition Contains three densities of the worlds most neutral dark ND filter, the ProStop IRND in 10, 6 and 3 stops. Includes an exclusive long-exposure technique booklet authored by Joel, plus a folding exposure conversion chart. 100mm is available with or without holder and 77mm and 82mm adapters. Made in the UK on the most advanced computer-controlled manufacturing equipment in the industry.