Up front, I simply love this magazine. The ergonomics created with finger grooves allow for easier grip points for reloads that don't slip with sweaty hands. The extra 5 rounds above factory offerings is always a plus. Its the little things with this mag, the rubberized baseplate to prevent deformations during mag changes, the stippling on the finger grip points, even the color offerings. I will say I did have a question when I function checked the mags but it was quickly answered but Thril. On a last round bolt hold open the bolt release on the right side will be stiffer than the factory, but when the spring is compressed (even with a single round) this stiffness is non-existent. I've worked with this on the range the other day, at first I didn't like the stiffness on an empty magazine now I love it. Its a small reminder to the operator that the weapon is empty. On top of my love for the magazine I can't say enough good things about Thril. The customer service and communication the offered throughout my entire purchase was so far above what I expected from any company. They let me know where they were in product development as things moved along and went above an beyond in taking care of me the customer. I said in an email to them that I would be a returning customer and I'll say it here too. I can't wait to experience their next product.