If your talking about casting them and searching its best to start with a 1/32 and let it slowly drop to bottom.The blade will slowly spin on the drop.Wait a sec before yo start your retr've back to the boat.They'll pick it up off bottom if there,if not try slow/fast,stop and drop,hop hop back to the boat.If no takers try again with different color jig head and bait color,again with the 1/32.If they are swallow stay with the 1/32,if they are deeper and biteing go to a 1/16 to get down there faster.The deeper and if biteing you can go to even heavier jig heads.I'll start with a black jig head,then olive green,orange,pink ect.ect..
Sometimes when the crappie are lazy they want chase the 1/16 just to get a snack,they'll turn their nose up to it and wait for something slower to eat.When they feel like they can whip anything in the lake a 1/16,1/8 curly tail roadrunner cann't be beat in my book.Thats how I start my search with the roadrunner type lure,thats all that I will cast.Only use round heads on long poles.......
However sometimes I have found out lately that nothing works not even a roadrunner in it best dressed cloths.