A magnetic lock is a simple locking device that consists of an electromagnet and armature plate.

Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified.

promotional gifts refers to articles of merchandise that are used in marketing and communication programs. These items are usually imprinted with a company's name, logo or slogan, and given away at trade shows, conferences, and as part of guerrilla marketing campaigns.