Guess the gap, guess your own stock Every round is two blind estimates at once: how far did the bar just drop, and which of my six blocks clears that but no more. You commit under a cup with everyone else, all four cups lift together, and the table watches the last block slide through clean or kiss the bar and get thrown out for good, out loud, with no judge but the rod itself.

One click, 0.5 mm, and you never see it The detent screw is 16 mm diameter and 118 mm long, threaded at a 2.0 mm pitch, with a 4-notch detent crown at its base. A quarter turn is one click; one click is exactly 0.5 mm of bar travel, felt and heard through the hood but invisible to the table. Travel runs 17.5 to 33.0 mm, 31 clicks end to end, and the crown holds each click crisp without letting the yoke's weight back-drive it.

The bar is the only judge, it can't lie The bar is a hollow 8 mm rod, 158 mm long, capped under 6 g, resting loose in two 4 mm V-saddles with nothing fastened. At that weight the lightest touch makes it rock or roll, so there is no judge to argue with and no call to make, either the bar moved or it did not. The saddles hold a 130 mm clear lane with nothing else in it.

Eight clicks hide the game's only secret The setter always turns eight clicks total: down 5 up 3, down 6 up 2, or down 7 up 1, so the bar always drops 2, 4, or 6 clicks, that is 1.0, 2.0, or 3.0 mm. The 78 mm knob hood swallows the whole hand so only the wrist shows, hiding which of the three patterns was used. Everyone hears eight clicks and sees the new gap; nobody but the setter knows where the turn reversed.

42 heights, always 0.25 mm off the bar Blocks are 20 x 20 mm with height H drawn from a 42-rung ladder, 12.25 to 32.75 mm in 0.5 mm steps, held to +/-0.05 mm face to face. Bar heights sit on the 0.5 mm grid and block heights sit on that grid plus 0.25 mm, so a block is never exactly level with the bar, the smallest possible margin is 0.25 mm, and no ruler is in the room.