Window blind having a restrainable bottom rail

A window blind comprising:

• a hollow horizontal headrail;
• a slat unit including a plurality of parallel slats disposed under and parallel to said headrail, each of said slats having two spaced apart holes;
• a hollow bottom rail disposed under and parallel to said slats;
• and
• a pair of pull ropes having a vertical section which passes through one of said holes in each of said slats, a turning section which extends below said vertical section within said bottom rail and which is inclined from said vertical section, a mounting section which extends and is inclined from said turning section, which extends out from said bottom rail and which is adapted to be fixed to a wall below said bottom rail, and a pulling section which extends above said vertical section and which is suspended from said headrail, said pulling section being operable so as to set a tension level on said vertical, turning and mounting sections;
• wherein said bottom rail has two spaced apart entrance holes adjacent to said slat unit, and two spaced apart exit holes provided below said entrance holes, said vertical section ending at one of said entrance holes, said turning section extending from one of said entrance holes to one of said exit holes, said turning section providing a frictional retention force to retain said bottom rail at a desired height,
• wherein said bottom rail has a left end and a right end, said exit holes being respectively disposed at said left and right ends, said entrance holes being disposed between said exit holes;
• wherein said turning sections of said pull ropes turn toward each other when extending respectively from said entrance holes to said exit holes;
• and
• wherein said turning sections cross each other and are twisted together within said bottom rail.