Those are air chambers that were purchased at a supply house. If they were made on the job they would have caps on them. Take a look at the top of them. There manufactured. We use to bye them by the case. They came in two lengths. If I remember correctly they were available in 6" & 12". It was cheaper to use them in place of a 3/4 x 1/2 x 1/2 with 12" of 3/4 copper and a cap.
John