Follow these step-by-step instructions to ensure a watertight and durable fit: Step 1: Measure and Dry-Fit 1. Measure the gap: Measure the exact width of your shower curb opening where the threshold will sit. 2. Mark the threshold: Transfer this measurement onto your 72" clear plastic piece using a pencil or dry-erase marker. 3. Orient the profile: If your threshold has a tapered or sloped design, note the correct placement. The higher, rounded, or sloped profile must face inside the shower to redirect water backward into the pan. Step 2: Cut to Length 1. Cut the plastic: Secure the threshold firmly and use a fine-tooth hacksaw to cut along your mark. Cut slowly to prevent the clear plastic from cracking or splintering. 2. Smooth the edges: Use a piece of fine-grit sandpaper or a utility knife to smooth out any rough edges or plastic burrs left over from sawing. 3. Test the fit: Place the dry threshold on the curb to confirm it fits snugly wall-to-wall without bending. Step 3: Deep Clean the Surface 1. Remove residue: Clear away any old silicone, soap scum, or debris from the shower curb. 2. Sanitize: Thoroughly wipe the threshold track area and the bottom of your new plastic strip with isopropyl alcohol. This eliminates invisible oils, which is vital for the adhesive or silicone to bond properly. Let it dry completely. Step 4: Secure the Threshold • Method A (If it has pre-applied adhesive tape): Peel back a small section of the protective plastic lining. Align the threshold precisely on your curb line under the closed door. Gradually pull the backing off while pressing down firmly across the entire length to activate the bond. • Method B (If using clear silicone): Apply a thin, continuous bead of 100% clear silicone caulk directly to the flat bottom of the plastic threshold. Carefully press it onto the curb. Wipe away any excess caulk immediately with a damp cloth or your finger. Step 5: Cure and Dry • Wait 24 hours: Avoid using the shower, splashing water, or moving the threshold for a full 24 hours to allow the silicone or adhesive tape to cure completely. Opening or shutting the door prematurely can shift the track out of place