Inclusion Criteria:  Male or female, ages 21-77 Current smoker with ≥5 cigarettes per day for ≥1 year history of smoking Screening CO ≥8 ppm Not currently interested in quitting smoking Willing to briefly switch from combustible to noncombustible nicotine  Have reliable daily access to a smartphone or tablet compatible with the iCO Smokerlyzer app:  Android 8 or higher, iOS 8 or higher Bluetooth-enabled device  Exclusion Criteria:  Current use of smoking cessation medications such as varenicline or bupropion Major chronic medical problems, including cardiovascular disease, diabetes Pregnancy (a urine pregnancy test will be administered at screening for all women of child bearing potential).