8" long tandem switch plates for covering two electrical devices stacked lengthwise. These specialty type long wall plates were common in apartment and condo developments, particularly in the Chicago area. Tandem plates were typically mounted sideways and configured with either a Decora receptacle or duplex outlet side by side with a Western Electric phone jack 548A or Sierra plug. Often, residents will remove the unused telephone jack and cover this long switch plate with the outlet opening stacked by a blank. Dimensions are 8.25" long x 2.75" tall, but the location of the devices within the plate may vary, so check spacing carefully.