The RiteFlo™ spacer is the only spacer that assures the NIH guidelines for correct inhaled flow rate. Optimal flow rate allows the medication to get deeper into your lung. RiteFlo™ is priced significantly lower compared to other similar spacers/holding chambers. This was done to allow patients the opportunity to always have a spacer to use with their inhaler. All other spacers require training for proper use because whistles are needed to adjust for proper inhaled flow rate. No training is required if you use the RiteFlo™ spacer since this is a built in feature.