Cell free DNA (cfDNA) analysis for the purpose of diagnostics is currently practiced for non-invasive prenatal screening of cell free fetal DNA (cffDNA), and is anticipated to be leveraged for early stage cancer detection via circulating tumour DNA (ctDNA) detection. The process can be expensive as cfDNA fragments originating from a source of interest (i.e. cffDNA, ctDNA) are greatly outnumbered by those from normal tissues. While different methodologies for enrichment are being devised to deal with this issue, recent evidence suggests that cffDNA and ctDNA may be largely degraded to a final size of a specific length range. Such a reality opens the door to enrichment via tight size selection. Coastal Genomics is working to validate its Ranger® Technology platform for automation of high resolution gel-based size selection. In this talk, we discuss progress on this front, and consider realistic implementation of size selection in the context of the tradeoff between assay specificity and sensitivity.