The correct spark plug and gap is crucial to proper ignition. Spark discharge is a breakdown in the air insulator between the electrode and ground. Yes - air is an insulator, a pretty good one at that. As voltage builds at the electrode, atoms in the air within the air gap gain electrons. This process is called ionization.
It's one of the reasons why our standard lenses are polycarbonate (thinner than standard lenses typically sold by other eyeglasses retailers). At Warby Parker, you can upgrade to high index lenses for an additional $30 whereas it typically costs $60 to $100 more.
Cost of Contact Lenses Compared With Eyeglasses. Some experts suggest the average cost of prescription eyeglasses is less than $300. If this is true, contact lenses cost more. Also, many people who wear eyeglasses do not purchase new glasses every year. But the cost of eyeglasses can increase significantly if you choose premium features, such as high index lenses, progressive lenses, anti-reflective coating and designer frames.