Avoid these like the plague!
Fitted some in a kitchen for an OAP customer today, found the centre line of the room both ways, marked a cross, put down the first 4 tiles.
Couldn't get the edges to align squarely, though I was cracking up - until I measured the diagonals of the tiles - 8mm difference on each tile. Completely out of square.
Tried another box, all the same. Consistent anyway.
I don't expect a carpet tile to be perfect, but these where completely pissed.
Careful use of several new knife blades & a roll of heavy duty double sided carpet tape & I got the job done.
I'll never lay the bloody things again!