Interlocking system slate is also called 'crazy mat'. The slate stones are calibrated and cut (sawn or hand chiseled) and then placed and glued in an order or randomly on a plastic or fiberglass mesh back sheet. The unique feature is that sheets are matching and interlocking with each other, giving a unique pattern look. It also makes the installation job easier at job site.
p015-interlock-p11
p015-interlock-p21
(old design)

s1120-fan-tile-p22 (improved new design)
p018-p015-interlock-p11
s1120-interlock-p51a
s1120-interlock-p51b
These following photos show how the interlocking system works, how the stone sheets match each other
Four sheets interlocking are demonstrated

Interlocking zoom in photo

Packing for the paving sheets