How does ZB-guardian/ Z-guard enhance the peak shape in a splitless injection?

In a splitless injection, the analytes and solvent enters the head of the ZB guardian/Z-guard as vapors. If the initial oven temperature is lower than the boiling point of the solvent, the analytes and solvent will condense on the walls of the column head.  This would result in broad peaks as  the analytes are not focused as sharp bands. If a ZB guardian/Z-guard is used, the solvent vapor starts to move through the ZB guardian/Z-guard, analytical column  and reaches the detector. In the mean time, the analyte travels the ZB guardian/Z-guard and focuses as a sharp band on the head of the analytical column. Thus  ZB guardian/Z-guard acts as a retention gap in a splitless injection resulting in sharp peaks.