Systems and methods for detecting supported small form-factor pluggable devices in an adapter are provided. An electronic component is mounted on the first substrate and arranged between the first substrate and the second substrate. An insert pipe protrudes from the main housing. The amplitude IL1 of a reproduced signal from the longest recording mark with the mark length of mT recorded on the first portion and the amplitude IL2 of a reproduced signal from the longest recording mark with the mark length of mT recorded on the second portion satisfy the relation 1<<1.