Inclusion Criteria:  Patient is 18 years of age or older. Patient is willing and able to comply with protocol requirements. Patient has confirmed diagnosis of CRS per International Consensus Statement on Allergy and Rhinology, Rhinosinusitis 2016 (ICAR:RS) guidelines. Bilateral disease in the frontal sinuses (Lund-Mackay CT score of ≥1 on each side) on CT scan within 90 days prior to enrollment. A successfully completed in-office balloon dilation of the bilateral FSO with no complication on either side that, in the opinion of the clinical investigator is amenable for PROPEL Contour Sinus Implant placement.  Exclusion Criteria:  Nasal polyps or other physical anomaly that precludes FSO endoscopic visualization. Oral-steroid dependent condition such as chronic obstructive pulmonary disease (COPD) or other conditions. Known history of allergy or intolerance to corticosteroids or mometasone furoate. Patients with a known hypersensitivity to lactide, glycolide or caprolactone copolymers. Patients with electronic devices in direct connection to the brain or the nervous system such as implantable neurostimulators (e.g. deep brain stimulation), programmable CSF shunts. Patients with monopolar pacemakers (older designs, with lower resistance to interference) or ICD's (implantable cardioverter defibrillator). Patients with implantable, body worn devices such as insulin pumps. Evidence of purulence coming from paranasal sinuses or ostiomeatal complex. Clinical evidence of acute bacterial sinusitis or invasive fungal sinusitis (e.g. bone erosion on prior CT scan, necrotic sinus tissue). Active viral illness (e.g., flu, shingles). Use of parenteral or injected steroids (e.g. Kenalog) 30 days prior to the baseline procedure. Use of oral steroids, budesonide or other sinus steroid irrigations/rinses or drops, nebulized steroids administered nasally 14 days prior to baseline procedure.