Blister-pack

A blister-pack is a relatively non-expensive package done in clear plastic foil which is thermoformed to match the shape of the product inside.  This form of package is widely used for consumer products of small dimensions because allows to show the product inside while protecting it.
 

The most usual blister pack is made of a formed shell sealed on a cardboard by means of a temperature sealing process. Shell is formed to best match the shape of the product, so it remains trapped inside.

For heavy products a full-made plastic blister pack is advised. This form of blister-pack is also used for high-value products since makes tampering more difficult.  It consists in a formed shell sealed against a plain clear film either by temperature or high frequency, depending on material welding capabilities.

In high frequency welding, plastic foils are heated when subjected to the action of a high frequency electric field until melting point is reached while pressing them.
 

These blister-packs are designed in a fashion to make them deliberately difficult to open and therefore eliminating any possibility of tampering with the product inside.