Product Details -For stopping flow, air testing and pressure monitoring -Lightest weight multi-size available -Their 2 ply or more cross-biased tire cord reinforcement allows for more controlled expansion of the plug -This design reduces the stress on the sidewall and eliminates end to end tears -Plug ends are reinforced with a steel Spider and trade; ring wrapped in fabric -Sizes are available to block flow in 4in through 96in diameter pipe