Currently in the UK we use the METRIC system for measuring weight but we used to use the IMPERIAL system. 

Many countries still use the IMPERIAL system.

Below is a comparison table which may help understanding of the difference.

IMPERIAL WEIGHT                            METRIC EQUIVALENT
4oz (Quarter Pound)                                               113 grams
8oz (Half-Pound)                                                    227 grams
16oz/1lb (One Pound)                                            454 grams

Although we are obliged to use Metric scales in our shop, all staff are trained to know the difference, so when a customer asks for 'a Quarter of' we can give them exactly what they want.