Economy gauges. Got mine long ago. the late '90s.
Mine serve the purpose, but I use them judiciously, as they won't tolerate
rough handling. Plastic restrictor/dampers, hoses that rot and split, and hose adaptors that need lock-tite applied to the threads (I super glued mine on) so they don't unscrew from the metal tubes. Works out ok tho, Syncs come out good. just use care when setting em up.