The popular Conedisc is a conehead which is flared out on the back end. The idea behind the flared design is to create a vortex in the water... which causes the materials behind the Conedisc to have more volume and movement. Also popular is to tie the Conedisc into the fly and keep materials such as marabou from lying down flat while in the current .
There are 9 Conediscs in a package. Each Conedisc weighs approximately 0.32 grams and is 8mm.