Casing Shoes
The casing shoe is generally used in caving overburden, where the "spun in" casing cannot be removed without the hole caving. For this problem, the casing shoe is designed without diamonds on the radius. This allows the shoe bit to stay in place at the bottom of the casing and accommodate other tools passing through the shoe, without danger of being destroyed by the diamonds in the bit. After operations are completed, the shoe is recoverable.

Casing Bits
A casing bit is usually set with diamonds and used to rotate the casing into solid materials where it can be withdrawn without the hole caving in, for the purpose of cementing other casing into place. The diamond casing bit has both inside and outside diamonds to facilitate making a hole with clearance, as well as, using the casing as a drill tube.

Acker Diamond Casing Shoes and Bits - "W" Design
Acker surface set diamond casing shoes and bits are available for the approved DCDMA flush joint "W" design casing. "W" casing bits and shoes are only available with box thread connections. Casing bits and shoes have a standard pin thread connection. Box threads are available on request.