All lamps have a specific “bulb type” designation that describes the shape of the lamp and the size of the lamp (diameter). The designation is a two part code consisting of a letter and a number. The letter indicates the shape of the lamp and the number relates to the diameter of the lamp in eighths of an inch. A “T” designation means “Tubular”, which in the form of a T-1 ¾ lamp became the primary package size for LEDs when they were first introduced and are still a standard form in much demand. . “T-1” is the base designation for a 1/8” diameter lamp, the smallest size “T” lamp. Other designations are based on the T-1 standard, i.e., T-1¾ is 1¾ multiplied by 1/8, or .219”. These were then converted to millimeter, so a T-1¾ is also known as a 5mm lamp.
MARUBENI Tech-LED sells 3 and 5mm LED PTH Lamps. The 3mm and 5mm lamps LEDs have different lamp shape and varies view angle you can choose. Once this occurred the diameter of the lamps more closely approximated the mm dimension. Other T-size lamps up to t-10 can be made as custom devices. Please contact us accordingly.