Minimum questions that you should ask any manufacturer of
"Emergency Building Escape Parachutes" include:

1) Are you a member of the Parachute Industry Association?

2) Do you make any other parachute equipment for use in  BASE jumping, Skydiving, or Military applications or other equipment that is US FAA Approved (or foreign equivalent)? 

3) Most emergency parachutes are approved by the FAA (or foreign equivalent), and while FAA approval is not legally required for parachuting from a building, is your parachute certified by the FAA (or foreign equivalent) or do you manufacture  parachutes under a quality control system similar to that required for emergency parachutes in CFR Part 21? 

4) What is the measured rate of descent for your parachute at the maximum operating weight limitation?

Answers:
1) should be Yes
2) should be Yes
3) had better be Yes
4) had better be less that 20 feet per second