FY-505 is the module below the B9A base. Into the base is fitted an FX-6A 9-pin 8 mm xenon arc bulb. Together they form a strobe module. This tube is still clear indicating little use. The glass will darken with use.
FX-6 series are called low cost strobes and are designed for observation of rotating machinery at up to 25,000 RPM. The maximum flash energy is 5 Joules with a maximum average power of 7 Watts. The maximum anode voltage is 1,000 V. These tubes can be fired at a maximum rate of 500 flashes per second corresponding to 30,000 RPM.
The FX-6A strobe tube. The main electrodes look like carbon blocks and the trigger (known as a 'sparker') consists of five wires configured as an inter-digital set between the main electrodes.
The FX-6A designation is at the top with the makers initials at the bottom of this image.
The FX-6A on its own.
The thin glass tube envelope is 20 mm in diameter and, excluding the base wires, is 70 mm tall.