**Updated stl to an improved model*** It's an improved version on previously made Rocksolid IPhone 4 Bumper.Instruction Video http://youtu.be/KZPcZmigoQwPrint with PLA. You can use supplied G-code or make some adjust if you wish.READ INSTRUCTIONS BEFORE USINGWARNING : There is almost no space between the phone and the bumper and requires some force to fit so be careful not to break anything such as power button, vibrate switch, your finger or IPhone.Print with fill greater than 80%, I've done with 100%. Otherwise horizontal layers won't stick well at thinner parts.Now the important part - Watch the instruction videoLay down the bumper and IPhone with the back panel up and volume/vibrate buttons facing away from you.Bottom left corner of the bumper (after step 1, bottom left corner is now on the right and facing towards you) has reduced overhang. Now lay the bumper down and fit your IPhone from up(as in from the air). Fit and align 3 other corners very tight.Slowly push in the bottom left corner until it's in place. You should hear a "click" sound. Make sure other 3 corners are still in place. Check the screen side(front) as well.If it doesn't make its way easy then tap it with your hand gently but firmly. It may require some force to push in. Once it's in, it should feel rock solid.