The newly developed bidding cards and special cards are made of foreign-built plastic materials that are high in strength and elasticity, not easy to break in winter time and washable in water.

• 新开发的塑料叫牌卡、塑料专用牌均采用进口塑料片材，据有强度高、弹性好，在冬天使用不易破裂也可在水中清洗。