I just got through watching the US open from Olympic C.C. in San Fran. That place was built in the 1920's. There was about 40 ft. between head's in the fairway. Most modern course's have about 90 ft. between fairway head's. I'll bet they have low water pressure there. Those head's had brass lid's, i'll bet they are older impact's. I also saw brass lid's on head's around the green's. I'll bet they reused what was already there. That say's something about the longevity of those type of head's considering they rebuilt those green's in the last 5 year's. And if you want to see some frying ryegrass then you need to check it out tomorrow.