Office display or sale space of wholesale jobbing or distributing establishments not specifically mentioned herein, provided that not more than 25% of the floor area of the building or the part of the building occupied by said establishment is used for making, assembling, remodeling, repairing, altering, finishing or refinishing its products or merchandise; and provided, further, that any resulting cinders, dust, fumes, noise, odors, refuse matter, smoke, vapor or vibration is effectively confined to the premises; and provided, further, that the ground floor premises facing upon and visible from a major street upon which the premises abut shall be used only for entrances, offices or display purposes.