The 'Brat' is an Irish mantle. Originally this garment was worn like a cape; the top two corners were affixed to the shoulders using penannular brooches.
Following the adaption of Highland wear for Irish regiments and Gaelic enthusiasts in the late 19th/early 20th Century, the Brat assumed the dimensions of a large Fly Plaid (1.5 yards square) and is now folded much the same as a Day Plaid.
Like the Day Plaid, a Brat is finished with a fringe on the two cut ends. A hand-purled fringe is also available at an additional charge. A Brat today is worn with a brooch on the left shoulder.
The folded fabric is much too thick for the brooch pin to fastened to the jacket. Instead the brooch, acts as a counterbalance and also prevents the Brat from slipping through the epaulette of a jacket.
Traditionally, the Brat would have been made using solid-coloured twill cloth, especially green or saffron. There is no reason, however, that it cannot be made using the modern Irish tartans.
The Brat, like the fly plaid, is usually reserved for more formal events.