Currently Being ModeratedDec 29, 2013 6:49 PM (in response to Denise-RS)
What Apple product did the come with? You are in a forum for pre-1998 Mac hardware that gets little traffic so, If we knew what iDevice you have, we can get you moved to a more active and relevant forum.
That said, it's hard to find any info with wattage from an order number (MB051ll/A). Can you find a 4-digit model number starting with "A" or "M"?
Searching sellers ads, it appears to be discontinued but originally intended for early iPhones and iPods. None of teh seller I foudn showed wattage. Apple's poor support seach function is not helping much.
Get a strong magnifying glass and look for pale grey printing on the charger. I did that with our iPad2 charger (not the same charger adn the 051LL) and "10W" is fairly clear.