This is a TOSHIBA TEC label product with part number LTX010010R1ST-BLU. It is a thermal transfer, non-perforated label designed for use with TOSHIBA printers.
These labels are 1-inch in diameter, have a blue color, and come wound out on a 3-inch inner diameter core with a 4-inch outer diameter.
They are supplied in rolls of 500 labels, with 4 rolls per case.