Shani yantra is used to pacify an afflicted Saturn and achieve Rajayoga through complete blessings of Shani. When Saturn is malefic in a horoscope, in transit or causes Sadesati, use of Shani yantra is very beneficial.
Mantra: Om Shanaishcharaya Namaha  

It helps person frees from debts, offers protection from accidents, cures diseases and anger/temper and ensures quick recovery from surgeries etc. Powerful for dissolving gossip / back slandering, criticism in office environment.
Mantra: Om Kraang Kring Kraung Sha Bhaumaay Namaha  

Anyone whose ruling planet is Moon in astrological analysis should keep this yantra in their room or use it. It provides the possessor with knowledge and peace of mind.
Mantra: Om Shraang Shring Shraung Sah Chandramase Namah  

When Jupiter is malefic, the use of Brihaspati yantra is very beneficial. It bestows power, rank and authority. Keeping this yantra in offices or business place in front of the person removes the evil eye effect from the outsider and negative energies. People who have less confidence can use this yantra in their pocket removes the nervousness and increases the fluency of talks.  

When Rahu (Dragon's Head) is malefic in the chart or horoscope, Rahu yantra is kept in the house or pocket to balances the malefic effects of the planet. Rahu yantra blesses the person with knowledge and deep understanding.
Mantra: Om Bhraang Bhring Bhraung Sah Rahawe Namaha  

Used to enhance the benefic effects and curtail the malefic effects of Mercury. If worshipped regularly, it improves the strength of nerves and gives the person control over senses. It gives wealth and all liquid assets to the person. In business it is said to increase the flow of cash.  

Ketu yantra is to appease the planet Ketu. When Ketu is malefic, the use of the Ketu yantra is very beneficial. The Ketu yantra promotes success in business, victory over enemies, and all round success. This yantra is also beneficial in the problems of death, debt, litigation, loss, bone disease, arthritis.
Mantra: Om Sraang Sring Sraung Sah Ketawe Namaha  

Good for those who deprived of happiness through termination of service, suspension or through opponents in office politics. The worshipper attains good health. Surya yantra enhances the peace of mind, gets favour from Superior. By the use of Surya yantra enemies are suppressed and it helps to eliminate the malefic effects of Sun.
Mantra: Om Hraang Hring Hraung Sah Suryaay Namaha  

Navgraha yantra is a combined yantra for all the nine planets and is divided into nine squares, each one with a talisman representing one planet. Navagraha is an extremely useful & beneficial yantra, since it’s worship strengthens benefic planets & increases their positive influence and pacifies malefic planets & neutralizes their negative effect. Navgraha yantra is recommended for all, particularly those whose planets are detrimental or malefic as per horoscope. Navgraha yantra should be worshipped life-long to ensure that you always get maximum advantage from your planets.
Mantra: Om Namodevaya Namaha  

The yantra is to appease the planet Venus. When Venus is malefic, the use of Shukra yantra is very beneficial. Shukra yantra bestows respect, love, attraction . Worshipping it in house or office will improve relationships with the people around to be harmonious.
Mantra: On Draang Dring Draung Sah Shukraaya Namaha  

This yantra consist of nine planets yantra carved in single plate.Keeping this yantra in altar place or in north east corner of the house will protect the individuals living in the house from the malefic effects of nine planets.