The performance of a fiber optic system depends heavily on the cleanliness of the interfaces. Dirt particles, grease, dust, etc. can have a highly negative impact on the transmission characteristics. They can actually destroy a fiber optic connection depending on the circumstances. If the connector is plugged in without first being tested, it could well be too late. The high pressure in the connection means that particles are immediately pressed in and this causes irreversible damage. This is why it is becoming increasingly important to test all connectors and adapters, and, if necessary, to clean them before they are mated – even new products that have just come out of the packing.