Jim, those Conti Ultralight tubes are my choice, only one puncture flat in the 4 years I used them. Same as yours, a sliver of glass that manages to slip through and get me on a cold and rainy afternoon. I watched for the various deals for 3 to 5 tubes and stocked up , but they are just sitting on the shelf, other than the single in my seat wedge.

I did change our daughter's Cannondale R500 to Gatorskins and Ultralight tubes when she came down last spring. She had Michelin Pro3 Service Course and their tubes, she had 3 flats on one ride with me, discovered that the Co-op she frequents, in Atlanta, had installed the rim strips wrong and they were cutting into the tubes. Never saw that before, either, the strips had a sharp edge that stuck up where it lapped. I showed her what they had done, she went home and gave them an ear full. And, she does know how to change a tire and tube now, I did a home study course in our garage for her. Had her do the work out on the road, learning by doing.

She is now a Ultralight and Gatorskin/Continental convert.

Bill