A steel cord (10) adapted for the reinforcement of elastomeric products comprises a core and a layer arranged around the core. The core comprises one to four core filaments (12) and the layer comprises three to ten layer filaments (14). At least one of the core filaments (12) have a first wave form and at least one of the layer filaments (14) have a second wave form such that the first wave form is substantially different from said second wave form.This allows to control the size of the micro-gaps and to guarantee rubber penetration.