530. Rino 530 - a waterproof FRS/GMRS radio plus GPS navigator
531. VMFA-531, Marine Fighter Attack Squadron-531
532. iRobot Roomba? 532 Pet Series robot vacuum for pet owners
533. Pipe Fitters local 533, Kansas City, Mo
534. Avia B.534, mid-1930s Czechoslovakian fighter plane; one of the last biplane fighers
535. BMW 535i sedan
536. SCR-536 Walkie Talkie The SCR-536 was the original walkie talkie, also called handy-talkie, the smallest of Signal Corps radio transmitter and receiver sets in World War II.
537. Coby DVD-537 - 5.1 Channel DVD Player with progressive scan.
538.
www.fivethirtyeight.com - political website focused on polling analysis and statistical forecasting
539. Studio539 - floral design studio in Providence, RI
540. 540 AM ESPN sports radio station in Milwaukee, WI.
541. 541 Tekmar Programmable Thermostat
542. John Deere 542 Loader
543. Unit 543 - a secret Imperial Japanese Army facility at Hailar that focused on the development of biological weapons during World War II - operated by the Kempeitai, the Japanese military police.