These clickers from Industrial Strength fit perfectly in septum piercings, but also do very well in various ear piercings.
These clickers fit piercing holes that are 1.6 mm in size, but with the help of an adapter these can also be adapted to piercing holes with a larger diameter. The measurements 6.3 mm and 7.9 mm respectively in the product description refer to the height of the jewelry. If you are unsure, a good tip is to measure with a normal BCR; if an 8 mm BCR is tight, it may be time to invest in the larger variant. All clickers are 1.6 mm in thickness.