Slow Spiral (Low Helix) Router Bits are designed to lessen the up or down force to help keep chip outs from happening on the top of the material. Great for more brittle substrates.

Upcut bits are the go to choice where having a clean bottom surface or getting maximum chip evacuation is most important. The up cut action of the bit pulls the chips up and out of the cut allowing for maximum chip evacuation. Because the chips are being pulled up this will result in a clean bottom edge of the cut