Reno:
The term TR is and was used to define straight blade receptacles, 120 volt, 15 & 20 amp. Prior to the mandate to require TR in resi, they were required in 517 and some child care facilities, either by design or some local 'code'. TR devices were 'spec grade' and pricey.
The types of covers within this thread may be better referred to as 'child resistant' or hopefully not offending anyone, 'idiot resistant'.
As I was trying to allude above, the covers & inserts are not electrician items, but ems a homeowner would buy & install.
The covers, as alluded to in the UL link had an issue with cord caps properly seating & possible fire situations as a worse case scenario.
