Convex glass is curved and often distorts the driver's ability to gauge the distance of other objects properly when viewed in the mirror. This type of glass is often preferred as it helps to widen the driver's visual field. In most of cars this is a standard type. Fitting instructions: (for self adhesive type mirror glass) Thoroughly clean and dry surface to which replacement glass is to be fitted. We recommend you use clean water and dry with a soft cloth. Carefully remove any loose glass and dust off any small particles. Do not apply outdoors in damp or cold conditions. Do not remove any glass unnecessarily. Where the original glass is bonded to the door mirror assembly, this will provide a sound base onto which the new glass will adhere.