A strain relief device is disclosed that allows the passage of at least one telecommunication cable therethrough. The exemplary strain relief device has a one-piece, rectangular tubular body, an external strength member securing section to secure strength members from the at least one telecommunication cable to the rectangular tubular body and a sealing member to provide an environmental seal between the at least one telecommunication cable and the strain relief device and between the strain relief device and a mounting structure into which the strain relief device is inserted. The rectangular tubular body has an outer surface and at least one cable channel extending between a first end of the rectangular tubular body and a second end rectangular tubular body.