Samsung S2 2500mAh Batteries original size

today i found this 2 batteries on amazon this are 2500mAh Batteries with original size less when 10€ what do you think ?
http://www.amazon.de/Cbury-Samsung-E...dp/B00TGMRIPI/
http://www.amazon.de/iFoxtEK-2500mAh...dp/B00E3SD02A/
ps sry links are in german