1, 2, and 3 designate STEEL TOOTH BITS.
1 for soft, 2 for medium, and 3 for hard formations.
4,5,6,7, and 8 designate TUNGSTEN CARBIDE INSERT BITS for Varying formations with 4 being the softest and 8 being the hardest.
1,2,3, and 4 are further breakdowns of formations with 1 being the softest and 4 being the hardest
1. Standard open bearing roller bit
2. Standard open bearing roller bit, air cooled
3. Standard open bearing roller bit with gauge protection which is defined as carbide inserts in the heel of the cone
4. Sealed roller bearing bit
5. Sealed roller bearing bit with gauge protection
6. Journal sealed bearing bit
7. Journal sealed bearing bit with gauge protection