MP3 model H100 - Service Support

I need to charge my RCA MP3 H100 when away from home computer - is this possible with an AC/USB Charging Adapter (RCA Handbook says only to use computer). I have such a unit but am wary of using this - specs are-“Worlwide Input 100-240V AC 60/50Hz. Output USB connector 5VDC max. 1A, stabilized”
Any advice would be welcome.