A quick and easy way of software sizing - estimation method. The method is used widely during sprint planning meetings where in the product owner would need make a quick decision, to prioritise a feature over other. T-Shirt sizes are : XL, L, M, S, XS - therefore estimation for developing feature could be with in these ranges - XL could be 2 weeks, L - 1.5 weeks, M-1 week, S-1/2 week and XS - 1 day.