Abstract: An SFO-box (1) suitable to receive at least one optical fan out module (6). The SFO-box (1) includes a housing (2) with a base (3) and a top (4) which in an assembled position encompass a mounting space (5) suitable to receive the at least one optical fan out module (6) therein. The top (4) includes first fastening means (7) and the base (3) comprises second fastening means (8) which from their layout are compatible to each other such that two assembled housings (2) can be attached to each other in a stackable manner by interconnecting the first fastening means (7) of the top (4) and the second fastening means (8) of the base (3).