GFCI devices are bulkier than standard receptacles, and when you add stiff older conductors, wirenuts, and possibly a grounding pigtail, the result can be a device that simply will not sit flush.
UL489, CSA, UL1077, UL1500. 1-3 poles, 3rd pole switched neutral. Maximum interrupting capacity 5,000 amps. Series trip. Handle, rocker, flat rocker actuator styles ...
UL943, UL1053, UL1500. 1-3 poles. Maximum interrupting capacity 5,000 amps. Series trip. Handle, rocker, flat rocker, push-to-reset actuator styles. Front panel mounted. Terminal option 10-32 threaded ...