If the GFCI consistently trips, it indicate end of life and GFCI must be replaced.  
If GFCI end of life, redder the GFCI itself incapable deliver the power, denying 
power to outlet & down stream. 
    
Fast Block assures simultaneous power interruption at downstream receptacles and 
outlets. 
 
Reverse Line-Load Measure Test- new design disables the RESET button function 
(will not latch) when miswired. There will be no power to both outlet and downstream 
receptacles. 

In 2003 requirements, if GFCI line-load miswired, they only require no power to 
"Line" side, but in 2008, require there is no power at both "Line" side and outlets.
 
2008 GFCI is required the end of life function 
In the UL 943 requirements, when GFCI lose ground fault protection, 
we called the GFCI end of life. When the GFCI end of life, it must be one of below:
A. use a visible or audible indication let the end users knows this 
   GFCI end of life and should be replaced. 
B. Render the GFCI itself incapable deliver the power. 

Warranty
If within the two years from the date of purchase, this G.F.C.I. unit fails 
due to defect in material or workmanship only, we will replace it free of charge. 
The warranty does not apply to case of where damage has been due to faulty 
installation, abuse, misuse, or unauthorized tampering and/or repair.