... 2 37U600*600*1800 YD166—37UWith the two pieces of layer board, 30 set screw, fan 2 32U 600*600*1600 ... YD166—32UWith the two pieces of layer board, 30 set screw, fan 2 27U 600*600*1400 ... YD166—27UWith the two pieces of layer board, 20 set screw, ... 18U 600*600*1000 YD166—18U With the one pieces of layer board, 20set screw, fan 21. Can tear open ...