The Universal CD Slot Mount was fairly easy to assemble, just 4 pieces came with it. It does come with directions, but I just eye-balled it and clicked all the pieces into place. When it came to putting it in the CD player, once again it was easy. The insertion part is only 1/4 of the size of a CD and once it's in the CD slot, you just tighten a knob on the bottom of the mount to secure it in place. So, yes, it does go INTO your CD player, but since I don't use the CD player in my car, this product is a nice fit for me.
Everything is adjustable on this CD Mount. You can swivel it from side to side, widen the brackets to fit larger devices, and rotate it. There's also foam padding on the back and sides to protect your phone and keep it snug (See pictures below). It doesn't stick too far out, probably 4" at most.
As for size, it doesn't stick too far out, probably 4" at most and hasn't gotten in the way of anything, since I've used it. Although it does hide the radio station display/ clock display, which sometimes does bother me.
Apart from the visual hindrance, this product has been great for me and I highly suggest it, especially if you don't use your CD player often. These mounts can be purchased on Amazon for less the $20.
I received one or more of the products mentioned above for free using Tomoson.com. Regardless, I only recommend products or services I use personally and believe will be good for my readers.