The bottom hole size:10x6.2 cm,pls made sure your original antenna base size le than it,otherwise,it can't be install. Back Shark Antenna Frequently Asked Questions Question 1: Is the color the same as the original car?Answer 1: This antenna applies the piano paint, and its color is very close to that of the original car. However, since the original car is often exposed to outdoor environment, its color will change, and may be a little different from the shark fin antenna. That is normal, please understand.Question 2: Will there be a gap between the shark fin antenna and the car roof?Answer 2:The bottom of this shark fin has a curve, which perfectly fits most car roofs without gaps. However, the roofs of a few hatchbacks and SUVs are flat, and there may be small gaps in the middle, which will not affect the performance of product. Customers can fix this problem by using double-sided adhesive tape in the middle.Question 3: How does the radio work after installation?Answer 3: This shark fin antenna applies thick pure copper wire and aerial. According to our test, the radio signal strength is as strong as the original car antenna.Question 4: Do I need to remove the antenna base of the original car when I install the item?Answer 4: There is no need to remove the original car antenna base. It has a hole on the bottom, and most models can be directly installed. If your antenna base is larger than the mounting hole, you can remove the entire bottom plate of the shark fin.Question 5: What should I pay attention to when installing?Answer 5: Clean the area around the antenna to ensure that there is no water or dust. Connect the copper wire to the base first and test the radio. Tear off the 3M plastic film and blow the 3M sticker with a hair dryer to make the 3M sticker softer and stickier. Then aim at the position (only one chance to stick, be sure to aim at the position), pre for 3 minutes after sticking, and keep dry for 2 days.If you like it, please give us 5 star feedback, thank you.If you have any question, please contact us, we willgive you a satisfactory reply, thank you.