This is an Odyssey Ai-ONE TRI-BEAM series putter. It's a #5 half-mallet size, with a center shaft (CS). I bought it new and took it out for one round, but it didn't suit me, so I stopped using it after only a few putts. I had brought another putter that day and used that one instead, so the actual number of times I used this putter during that round was only a few. I'm selling it because I don't plan to use it in the future. Thank you.