A dust cap adapted to fit within a fiber optic adapter. The dust cap includes a dust cap body having a back adapter end and a front knob end. The dust cap body is shaped such that the back adapter end has a press fit with a fiber optic adapter. An opening accommodates an adapter ferrule and a flange is secured in an adapter by a stabilizer and projection. The dust cap also transmits laser light along a longitudinal axis of the solid mass of the dust cap body from just beyond the back adapter end to just beyond the front knob end.