It is NOT a replacement for the factory pan.  This expanded pan is made to be attached to your existing pan.  It can be attached by welding or riveting.

This expanded pan is made for serious cat trappers.  It can also be used for everything you target with  #4 Long Springs.  It is made with the cut out to fit the Victor #4, but will fit most #4 longsprings.  It is made from 16 gauge steel, and comes ready to weld on your traps.  It can also be bolted or riveted to your traps, but does not come with the required hardware.

Note for installing these: The expanded pan is cut to fit around raised pan post on a Victor long Spring.  Take a vice grips and hold the expanded pan on the factory pan in position and weld on. 

Advantages:

Expanded Pan - Larger surface area than a stock pan.

Made specifically for the Victor # Long Spring trap, but will for on almost all longspring.  Sits on top of the existing pan to make for easy installation.  Pan fits between springs, and pan always has a full range of motion.