a

Excess plastic on bottom edge top left-side.

a

Mark between stud 2 and 6

a

Excess plastic on right hand side of brick

a

Large mark next to slot

No excess plastic on bottom side of brick

a

Excess plastic on bottom side of brick

No line between stud 1 and 2

7mm pip - recess 3 from left/top in upper right quadrant small sloped

a

7mm pip - straight stud recess edges (compared with the others)

d

6mm pip - recess 3 from left/top in upper right quadrant small sloped