This group of alloys consists of copper with the major alloying element being tin. The presence of tin provides high mechanical properties, but with it somewhat higher metal cost. High tin bronzes are particularly suited for certain applications for which the less expensive bronzes are not suitable. Alloys in this group are particularly resistant to corrosion caused by certain specific materials. Bearings using these alloys must be very carefully aligned and positively lubricated, and they tend to require harder shafts than do the higher leaded bronzes.