Logo: modern logo
Inner wall: thin with vertical ridges
Inner ribs: Between the outer ridges on the long and short side. There is a double line on one long side of number 2.
Inner tubes: gripper tubes (octagonal inside).
Flowrib / center line inside top surface: No.
Mold pip: on the stud.
Mold number: 181, below the left tube.
Mold position numbers: 1 to 8, also below the left tube and separated from the mold number by a dash (-).
Intellectual property protection: None.
Design ID (3001): Yes, above the left tube.
Remarkable features: Minor mold error on the number 2 brick.
Colors known: White, Yellow, Blue. Gray.
One of the long walls of this brick has a double inner rib.
The moldmaker made a minor error here.