The ideal solution for modified exhaust systems that ensures a quiet morning start. Crafted for simplicity, just push and twist the silencer into place before starting your car, and effortlessly remove it using the knurl when you're ready to drive. Compatible with cars and motorbikes. Results may vary but a noticeable difference is heard when using this product. In some cases, start-up noise levels could be perceived as halved (10db reduction). See video. Experience reduced noise levels to ensuring a quieter environment for both you and your neighbours. Choose the best fit for your system with sizes ranging from 2 - 5.5 inches, covering metric units as well. A tapered design ensures a snug fit even with the most non-standard sizes of circular exhaust tips. Please Note: This version only works with circular exhaust tips only. Warning: It is made of specialized plastic so should not be left in the exhaust for more than a few minutes after starting. Should only be used when the exhaust is cold or warm to the touch. Measure the internal diameter of your exhaust tip, select the correct size from our list. Size options are in inches. If measuring in millimetres please use the table below and select the size that has your measurement closest to the middle of the range. As some overlap in sizes. Adjust the quantity based on the number of exhaust tips on your system. Compatible sizes: 2.00” = 49-53mm, 2.25” = 55-59mm, 2.50” = 61-66mm, 2.75” = 67-73mm, 3.00” = 73-79mm, 3.25” = 79-86mm, 3.50” = 85-92mm, 3.75” = 92-99mm, 4.00” = 98-106mm, 4.25” = 104-112mm, 4.50” = 110-119mm, 4.75” = 116-125mm, 5.00” = 122-132mm, 5.25" = 128-139mm, 5.50" = 134-145mm. For additional sound control, it allows you to add fireproof wadding into the device. Built in attachment holes to thread cord, helps keep your silencers together and aid for easy removal. Fireproof cord is recommended. (Both Not Supplied).