It is circle Ring lamp.
The interfaces of T5 ring light tubes can be turned up and down by 30 degrees, and can be moved about 1cm from left to right to facilitate installation.
The replacement lamp has parameters to see the parameters, without parameters outside diameter, find a close buy.
The lamp tube is an accessory, which must be close to the original, and the wattage and size are proportional to the size, which can not fit.
The diameter of T5 is a little thinner than T6, and the outer diameter is similar.