1538-P1 strobotron

This device is 30x19mm overall and has a B9A base.

This is a strobotron used in Strobotac stroboscopes. The two metal blocks are anode and cathode. The five metal rods aimed into the space between would be held at a potential between anode and cathode via a resistive divider to even out the charge density. These guide the arc along a known path, reducing jitter. The support lead of one block has a metal cylinder attached with an electrode held inside the cylinder in a ceramic 'tube'. This electrode is a preionizer and keeps the gas slightly ionized, reducing jitter by ensuring there are ions present to begin the arc cascade. This is connected via a high value resistor so the current through it is small.