The protective tent (Wyl. bsrung gur) and protective spheres (Wyl. bsrung 'khor) are meditated upon in Vajrayana sadhana practices to prevent any negative influence from entering the practice space. It is usually done after expelling the obstructing forces (Tib. gek) and preserved throughout the whole duration of the practice. The traditional example to illustrate this is of thoroughly locking oneself in after expelling thieves out of the house.