Streaky refines the low end of a mix by using a multi-band compressor and expander, such as the FabFilter Pro-MB.
The idea is to divide the low frequencies into two specific bands, one with compression, and one with expansion.
The compression band is set to below 115 Hz and aims to tighten and control the sub frequencies. The expander band is side-chained from the sub band and enhances the upper bass range from 115 Hz to 350 Hz. So whenever the sub frequencies are reduced, this band adds punch back in.
The combination of the bands contributes to a lively, moving low-end that is clear and controlled.