A:AnswerYou can mount this TV to a wall mount that supports the 400 x200 pattern, use M6 x 10mm screws. See the instructions that came with your wall mount for more
information about how to correctly mount your TV.
A:AnswerPlease check the User Guide available on
https://files.bbystatic.com/ycVAit0xrSwXKxX8S13UfA%3D%3D/Insignia%2BNon-Connected%2BTV%2BManual_17-0791_V1_EN_Final_lr.pdf
A:AnswerThe A20 and A21 most likely means the year of manufacturing. The A21 being the more recent. Thus having less reviews. Meaning a lower rating. Basically the same TV, different model year.