I have over 62 years of experience in many facets of electronics design and repair. I have been working with tubes since I was 12 years old. I am an active ham radio operator and have been for 62 years.
You are buying a trio (3) lot of the well regarded 1955 RCA long black plates. top angled "D" getters. 12AU7 preamp tubes. These tubes were born in 1955 in the USA. No shorts and are ready to use for your next audio project(s).
Matched Quad (4). Long Ribbed Plate. Made very early in 1956 with small logo. Diamond on Bottom. Tested in my preamplifier to make sure working as intended with no issues at all. I will almost always reply at least within 24 hours.
From a larger lot of RCA / Conn tubes mostly from the 50s/60s. Tube are matched by Gm. Power tubes like the 6L6 are tested only with the 686 which includes plate current (Ip), shorts and gas tests.