SOURCE

<div class="timer">
    <div class="top text">2</div>
    <div class="box">
        <div class="front box_item text">1</div>
        <div class="back box_item text">2</div>
    </div>
    <div class="bottom text">1</div>
</div>

.timer {
    position: relative;
}
.top, .bottom {
    width: 200px;
    height: 100px;
    background: #000;
    overflow: hidden;
}
.top {
    line-height: 200px;
}
.bottom {
    line-height: 0;
}
.box {
    position: absolute;
    top: 0;
    width: 200px;
    height: 100px;
    transform-style: preserve-3d;
    transform-origin: bottom;
    transition: all 1s ease; 
}
.box_item {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    overflow: hidden;
}
.front {
    background: #000;
    line-height: 200px;
}
.back {
    line-height: 0px;
    background: #000;
    transform: rotateX(0deg) rotateY(-180deg) scale(-1);
}
.text{
    font-size: 100px;
    color: #FFFFFF;
    text-align: center;
}
.box:hover {
    transform: perspective(200px) rotateX(-180deg);
}