EK-1 or Eerste Kwaliteit are the term used for Indonesian Robusta Coffee with the size of screen 16. The term means First Quality in Dutch.
EK-1 Grade 5 120 Defects means that the beans are grade 5 based on the National Standards of Indonesia (81-150 defects), with this type having around 120 Defects
Indonesian Robusta coffee uses classifications like AP, ELB, or WIB to indicate the bean’s size, grade, and processing style. Some of the common terms include:
English 
Chinese (China) 
Chinese (Taiwan) 
Indonesian