The Glock extended aluminum magazine base plates are machined in the USA out of a solid block of aluminum. They are solid and do not add any additional rounds. Many shooters requested this for the added weight. They do weigh 39.5 grams compared to 3.5 grams of the factory original plastic base plate. This added weight helps them drop free faster and more consistently. And, now you can color coordinate to match your other accessories or be able to spot your magazines at a glance. Does not fit the G36.