Looks interesting. Seems like it sells at $2.5 a piece at the cheapest, hopefully retails at a lower price. The design is creative and sleek. However, how do I

Looks interesting. Seems like it sells at $2.5 a piece at the cheapest, hopefully retails at a lower price. The design is creative and sleek. However, how do I know which size is for my device? Wondering if it will triumph over the ease of a piece of tape for the average consumer.