You have a U-Matic cassette
Did you know that U-Matic was one of the first videotapes in a closed cassette? Sony launched this product for consumers in 1971, but it was mainly used by companies and educative organisations because of the high cost. U-Matic tapes could store up to 30 minutes of video on the Small Cassette (U-Matic S) and up to 75 minutes on the Large Cassette.