In general, long and thin (high aspect ratio), flexible long pips are the best for chopping. Flexible, high aspect ratio long pips will return a lot of spin, and some can be unpredictable. Wide spreaded pips (low pip density) will make the rubber more unpredictable. Rough top sheet (dead) will make it unable to produce spin, While smooth top sheet is spiny. Wide and/or shorter pips with thick sponge are best suited for an aggressive blocking & hit style.