Our production codes are embossed (stamped) into the plastic film.  Since they are not printed, they can sometimes be a little hard to find.  But knowing where to look can be a huge help.  

For Reservoirs, turn the reservoir to the back and look for the vertical seam on the left.  Once you locate the seam, you can find the code embossed about 1"-2" down from the top. 

If you cannot locate the code, please enter "0000" on the warranty claim form.