DESIGNED TO LIFT OR LOWER TWO GUY'S OR 600LBS. CAN BE USED BY ONE PERSON TO RAISE OR LOWER HIMSELF. ANTI-REVERSING PULLYS ALLOWS YOU TO HOLD OR LOWER A LOAD WITH VERY LITTLE EFFORT. EXTRA SAFETY FEATURE IS THE ASCENDER, IT HOOKS TO THE ROPE AND TO YOU. SO IF YOU ACCIDENTALLY LET GO YOU DON'T FALL OUT OF CONTROL.