Ever since I bought my Glock 19, I’ve upgraded it with a few enhancements, one of them is an extended magazine release. The reason is I find it a little hard to depress the mag release button without having to shift my grip too much. Quickly bought one from MidwayUSA and after a couple of minutes struggling with the small spring tension, I finally got it installed. It worked very well right up to the point I had to carry the Glock in my IWB Crossbreed Supertuck holster.
The extended mag release protrudes out from the frame a little too much for IWB carry and keeps getting engaged while I’m seated or while moving around. This caused my magazine to release prematurely and drop out from the gun fairly frequently. This problem doesn’t exist if you use it with OWB type holsters because you have more clearance between the gun and your body.
Seeing my dilemma, a buddy of mine who works at Zev Technologies (Glockworx) sent a prototype magazine release to me a few weeks ago. I’ve been carrying it in my Crossbreed holster for two weeks now and it works wonderfully. It’s the best of both worlds actually, it sits flush against the frame and yet makes it easier for me to engage the mag release.

How?
It’s cut a little shorter than the stock mag release. 
To compensate for not being able to press the mag release as much as a stock one, they moved the spring tension “hole” forward just a hair. This makes it easier for you to drop the magazine. It is in essence, shorter, yet easier to depress than a stock mag release. The feel of it is very similar to the extended one, but without the detriment of accidentally releasing the magazine when carrying it close to your body.

(Top to Bottom : Glockworx prototype, Stock mag release, Extended mag release)
Overall, I’ve very happy with this dual benefit release mechanism. If they had this product available, I would not hesitate to buy it or recommend it to my friends who carry a Glock.