Open price indicates the starting price or the closing price of HDPE - Injection for the previous day. The close price is the price when the trade had ended for the day for HDPE - Injection. HDPE (High Density Polyethylene) Plastic Sheet 1/2" x 24 . Item Description: HDPE (High-Density Polyethylene) Plastic Sheet 1/2" x 24" x 48" Blue lor.