Based on this product's specifications, here are some alternatives and similar models
Battery t6 power for Asus X556U — 4500mAh, 34Wh, model NBAS0135
Summary description:
Replacement laptop battery by t6 power compatible with Asus X556U. Capacity 4500mAh (34Wh), model NBAS0135. Designed for restoring mobile runtime of your notebook, suitable for everyday use, office work and travel. Provides comparable operating time to the original battery and straightforward installation in supported Asus X556U models.