Nikolay Ivanov

Hi. I just registered to ask the same question i already asked on cinema5d. Hello. Does anyone know where i can buy a set of split-field diopter lens filter in the size for my 4x4 or 4x5.6 chrosziel mattebox. I'm very interested in purchasing but all i can find is round split diopters. On the commercial set our focuspuller has a set of old Russian LOMO split diopters made for 6x6 mattebox. But i can't find any unformation regarding this. Can anyone help me find out anything, where to buy, who produces now? Beforehnd thankful, Nikolay. Hope anyone can share some information with us.