ZN and ZF could be 0.01 ticks. But ZB depth is too shallow for 0.01 tick increment. About 10 years ago they changed ZB from 1/32 ticks to 1/64 ticks but they had to revert back after a year to 1/32 because each level was too thin. There was not a multi tick wide spread as you might think, but each 1/64 level was populated with about 60 contracts. Instead of several hundred contracts when the tick size is 1/32. Basically liquidty/depth shrank because the Market Makers and scalpers didn't like the smaller spread.