An SSL certificate ensures your clients a protection of their data by ensuring the authenticity of the organization. Contrary to the Basic SSL, the install process of the EV certificate implies a verification of your organisation. Thus this validation is strict and rigorous. Your domain name appears directly on your users' navigator, which is a security quality indicator. According to numerous studies of the issuers, the green bar is a factor of increase of the conversion rate !
The SSL EV certificate guarantee a maximum security level. This requirement allows you to gain the confidence of your users especially for the e-commerce websites.