KPMI, exhaust valve guide. Manganese. STD

Maganese bronze. Standard size: 0.6250" O.D. (15.88mm); 0.3745" ID (9.51mm); 1.91" OAL (48.51mm). Manganese bronze is softer and less durable then C630 bearing bronze but will allow a lower cost and reaming to size is quick and easy and finish can be done with simple tools like a ball hone and an electric drill. Rapid heat transfer and good lubricity.