The simplest and most versatile of Corrosion Monitoring devices.
Used in gaseous or liquid environment, Coupons reveal the type and extent of the corrosive attack.  

Different types of coupons are available, depending on the type of use:

Strip Coupon - Disc Coupon - Scale Coupon - Crevice Coupon.
Corrosion coupons are
weighted with resolution < 100 g, tagged for identification and packed in an envelope impregnated to avoid moisture.

More technical details