Kirkland Minoxidil is primarily available in a 5% concentration, which is the clinically proven strength for treating androgenetic alopecia. Buyers must distinguish between the Liquid (Topical Solution) and Foam versions. The liquid version typically contains Propylene Glycol, which aids absorption but may cause skin irritation, while the foam version is often preferred for sensitive skin and faster drying times. Ensure the product is labeled for external use only and check for a clear expiration date, as the active ingredient's efficacy degrades over time.