SOURCE

<div></div>

div {
    width: 100px;
    height: 50px;
    /* background-color: blue; */
    position: relative;
    border-radius: 8px;
    border: solid gainsboro 1px;
    background-color: white;
}

div::after {
    content: '';
    width: 0;
    height: 0;
    display: block;
    border-bottom: 10px solid transparent;
    border-top: 10px solid transparent;
    border-right: 10px solid transparent;
    border-left: 10px solid white;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    right: -20px;
}

div::before {
    content: '';
    width: 0;
    height: 0;
    display: block;
    border-bottom: 11px solid transparent;
    border-top: 11px solid transparent;
    border-right: 11px solid transparent;
    border-left: 11px solid gainsboro;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    right: -22px;
}