The information on our website is not complete or clear enough. Thank you for pointing this out. The Slip by Slip model of HV (and DV) are PVC. The rest of the HV models are glass-filled polypropylene, a stronger, lighter material than PVC or ABS. The HV passes all the same strength tests as the DV valve. I will make this difference in the Slip by Slip model material clearer on our website. Thank you for your interest in Rain Bird products.