These are simple and do the job by allowing dry fire practice with absolutely zero chance of a negligent discharge. By breaking down your weapon and inserting into the barrel they do not allow a round to be loaded into the chamber. By protruding out the barrel a bit they indicate a firearm rendered inable to fire. Great product.
Pros: Ease of use - Safety
Cons: none
This review was written in the old system and had content requirements that are different than reviews written today.