Usage Tips:Product information Product Name: Black Silicone Rubber Hole Plug Material: Silicone Rubber Shore Hardness Range 40-50Temperature Resistance C (from/to) -40 C to +250 C Function: Waterproof and Sealed Specification Size: 2.5mm30mm Colour: 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, Etc. Scope of Application: All Kinds of Pvc Pipes, Steel Pipes, Equipment Dustproof, Sewer Pipe Clogging,Blocking Various Aluminum Plate Holes, Etc. Can Be Used As Spray Plugs, Test Tube Plugs Warm Reminder, the Pictures Are for Reference Only, and the Size, Color and Printing Are Subject to the Actual Product. Purchase Notes:The Size in the Specification Option Is the Size a in the Picture, That Is, the Size of the Part.The Small End of the Rubber Stopper Is Inserted into the Hole.When Choosing a Rubber Stopper, Try to Choose a Size Larger than the Actual Measurement Port.Only to Achieve the Sealing Effect, Not to Fall off.