Watch Tower History: The Watchtower (IBSA) recordings (truthhistory.blogspot.com)
Those my friend are Transcription records, which were 16 inch in diameter, ran at 33rpm and played from the centre outwards – a problem for collectors who wish to play surviving copies today. The records are rare today because the users were asked to destroy then when they became worn and the sound quality deteriorated. From about 1931 they were used in sound cars and later on played in rented halls and then on radio stations.