20"x 4-1/2" Big Blue single O ring type filter Housing without head O ring
* Please CONTACT US first before buying this sump. We carry many models and this one may not fit your system head. We are not responsible for the incorrect purchase and this item is a final sale. Send us a clear picture of the existing system you have from the top bracket side, system side picture, and front system picture so we can recognize the model you have.