What they do is, take a tennis ball and apply PVC tape all around it in a circular shape (making sure you dont pull the tape too hard cuz it will make the ball go out of shape..takes a couple of times to learn the art). Now the ball is ready, special ultra light cricket bats(costs about $2 a piece) are used and the surface is usually a cemented floor or thick plastic sheet placed on the ground to make the ball skid with the speed of light. Since the ball doesnt hurt on the impact, you dont need to practice in the nets, matter of fact there maybe 15 teams playing a 20/20 match inside a single 50 yards ground. Youngsters also play with tape ball in the streets all over Pakistan since there is absolutely no protective gear required. Yes, it makes cricket affordable, lightning fast and very exicting but here are the cons, no lbw out rule, now thats a bummer cuz the batsman never develops the skill and consciousness of how to save himself from getting lbw out. The bats are extremely light and extra wide, and the ball is very light and travels with much different speed and momentum off the pitch than a regular cricket ball. These variations make batting a whole different story.
Usually a youngster in Pakistan starts his cricketting career by playing with tennis ball for the first 10 years are so which itself implants the wrong basics right at the start. And if the basics are not right, everything built on them will not be right.

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Had cricket been a religion, Imran Khan would've been the god.