Metal dome array ( dome array) is used in the early period of metal dome arrays industry. Metal dome contacts are attached under Maylar ( one layer of adhesive PET film) . On the sheet, there is an air hole for each dome contact and it is essential for good click-feeling. Character: 1) light & small 2) Nice handle & returned dome with breathe freely hole on metal dome. 3) Mainly used in cheap single layer PCB. Best Technology Co., Ltd., your best source of metal dome array & metal dome sheets from China! http: / / www.metal-domes.com http: / / www.metal-dome.biz