US Patent 11199670 Transceiver module assembly having stopper positioning

A length of a protection wall, which is greater than a length of projection of a connecting end portion of a plug connector from opening end portions of an upper case as well as a lower case of an optical module, is set to be smaller than an interval between a contact surface of each of lower stopper pieces of a receptacle cage to come into contact with an end surface of a side wall as well as an end surface of an end surface of the lower case and an opening end surface of a slot of a host connector.