The addition of a suppressor, dirty conditions or even switching ammo are all factors that can lead to undesirable gas settings on your rifle.Our patented design was developed, tested, and fielded by Special Operations who required the ability to run suppressed or unsuppressed without the need for tools for readjustment.The Select Adjustable Gas Block has 30 settings allowing specific, fine-tuning to each suppressor or ammo type. Once tuned, this gas block enables the operator to make on-the-fly adjustments as needed with a simple throw lever.