Abstract: A filtration device for separating filtrate and concentrate from a solution may contain a variable dead stop feature. The apparatus includes a housing with a means for collecting filtrate and a multiple sided filter unit insertable within the housing. The filter unit contains a semipermeable membrane thereon for separating filtrate from concentrate and a means for directing filtrate to a discharge within the housing. The apparatus also contains a means for preventing concentrate within the housing from escaping through the discharge opening of the housing.