From Wikipedia -
The 250-person Senate is composed of 194 members selected by the ruling junta. Fifty senators represent 10 professional and social groups: bureaucrats, teachers, judges, farmers, and private companies. A shortlist of 200 were proposed to the NCPO which made the final selection of fifty. The remaining six Senate positions are reserved for the supreme commander of the Armed Forces, the defence permanent secretary, the national police chief, and the heads of the army, navy, and air force, who are all senators ex officio.[4] As of 2020, military or police officers make up the Senate