The bottom hole size:10x6.2 cm,pls made sure your original antenna base size le than it,otherwise,it can't be install. Please buy Super shark antenna,it fit bigger base. Frequently Asked Questions Question 1: Is shark same color with original car color? Answer 1: The shark fin color very close the original color,however, the car due to long-term exposure to outdoor, erosion by rain and snow,the color has changed, so impoible exactly the same as color,please understand. Question 2: Shark installed on the roof have a little gap, is appropriate? Answer 2: Shark fin at thebottom have littlearc,most of sedan models no have gap,few hatchback models and SUV models roof is flat,there may be have a little gap,it does not affect the use.You can use adhesive in to the gap. Question 3: How about the radio signal effect after installation? Answer 3: This antenna using purification copper fittings,through our tested,the signal close to the original car antenna. Question 4: What should be note when installing? Answer 4: Clean around antenna base,be sure not have water and dust,first connect the cable and base,test the radio,if it is ok,than installing,heating 3M adhesive with hair dryer before you install,it will become soft,viscosity will increase,only have one chance to paste,so be sure to alignment the positionpreing 3 minutes after pasted,keep dry in 2 days. If you like it,please give us 5 star feedback,thank you. If you have any questions, please contact us, we will give you a satisfactory reply,thank you.