Model 129 generally refers to a DIY inverter board / inverter kit (not a finished branded boxed inverter), commonly used in hobbyist and low-cost home inverter builds.These kits are designed to convert 12 V DC (from a battery) to 230 V AC (50 Hz) for powering basic appliances.

Model 126 usually refers to a family of 12V square/quasi-square-wave inverter boards or Inverter kits commonly sold for hobby, repair and low-cost home backup use. Typical ratings you’ll see are 650-850VA (Some vendor listings also show higher variants such as 1,450 VA)