The difference between 15A and 15B is that. 15B is with aviation potentiometer material. Universal 15 Amp 1/2 wave self excitedDip-SwitchProgmmable avr Voltage regulation Less than 1%;220 / 440VAC programmable input Rugged compact design;Starting tension mechanized on ramp;With protection under frequency roll EMI Suppression;15Amp high capacity integrated fuse Voltage: 220 / 400VAC 1 Phase 2 of Power input voltage: 180-240VAC 1 Phase 2 of Output voltage: Max 90 VDC at 240VAC input Current: Continuous 6A, intermittent 12A for 10 secs Resistance: Min.10 ohm, maximum 100ohm Build voltage-: Residual voltage in terminal avr more than the 5VAC Voltage regulation: Less than 0. 5% with 4% engine Operating temperature: - 40 Celsius to + 65 Celsius Storage Temperature: - 40 Celsius to + 85 Celsius External volts Adjutment: 7% with 1k ohm 1 watt trimmer EMI suppression: Internal electromagnetic filtering interference Power dissipation unit: Max. 8 watt Often protection: 60Hz system preset knee point to 57Hz / 50Hz system preset knee point to 47Hz Colour:Black Material:plastic Package Contents: 2 * Generator accessories Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.