Product Name: Black Silicone Rubber Hole Plug Material: Silicone Rubber Shore Hardness Range: 40-50 Temperature Resistance: -40°C to +250°C Function: Waterproof and Sealed Specification Size: 2.5mm–30mm Color: Black Shape: T Type Packing Quantity: 50 pcs Features: Corrosion resistance, acid and alkali resistance, high temperature resistance, anti-ultraviolet, anti-aging, long service life, high and low temperature resistance Scope of Application: Suitable for various PVC pipes, steel pipes, equipment dustproofing, sewer pipe blocking, and covering aluminum plate holes. Can be used as spray plugs or test tube plugs. Note: Images are for reference only. Actual product may vary in size, color, and printing. The listed size corresponds to dimension 'a' in the illustration, which refers to the part inserted into the hole. The smaller end of the rubber stopper is designed to be inserted into the hole. For best sealing performance and secure fit, select a size slightly larger than the actual hole diameter.