New Walker- Mcdonald medium formation, open bearing bits. Available in 4 3/4", 4 7/8", 5" and 5 1/8". 2 7/8" api regular pin. Air or fluid applications. Great water well, geothermal, mining, workover or hdd bit. Walker- Mcdonald was the best small bit manufacturer before being bought by Varel mfg. We found a large quantity of these bits over seas and we have made them available at a great price.