HTML :
<a href="#" class="btn-slide">CSS :
<span class="circle"><span><b>→</b></span></span>
<span class="title">Slide to Unlock</span>
<span class="title-hover">Unlocked!</span>
</a>
.btn-slide {font-family:arial;font-weight:bold;color:#333;
position: relative;
display: inline-block;
height: 50px;
width: 200px;
line-height: 50px;
padding: 0 20px;
-moz-box-shadow:0 1px 0 #fff;-ms-box-shadow:0 1.3px 0 #fff;-o-box-shadow:0 1.3px 0 #fff;-webkit-box-shadow:0 1.3px 0 #fff;box-shadow:0 1.3px 0 #fff;
border-radius: 50px;
-moz-border-radius: 50px;
-webkit-border-radius: 50px;
transition: .5s;
-webkit-transition: .5s;
border: 1px solid rgba(0,0,0,0.15);
}
.btn-slide:hover {
background-color: #b6b6b6;-moz-box-shadow:0 1px 0 #fff;-ms-box-shadow:0 1.3px 0 #fff;-o-box-shadow:0 1.3px 0 #fff;-webkit-box-shadow:0 1.3px 0 #fff;box-shadow:0 1.3px 0 #fff;
}
.btn-slide:hover span.circle {
left: 100%;
margin-left: -45px;
background-color: #b0b0b0;-moz-box-shadow:0 1px 0 #fff;-ms-box-shadow:0 1.3px 0 #fff;-o-box-shadow:0 1.3px 0 #fff;-webkit-box-shadow:0 1.3px 0 #fff;box-shadow:0 1.3px 0 #fff;
border: 1px solid rgba(0,0,0,0.15);
}
.btn-slide:hover span.title {
left: 40px;
opacity: 0;
}
.btn-slide:hover span.title-hover {
opacity: 1;
left: 40px;
}
.btn-slide span.circle {
display: block;
background-color:#b0b0b0;-moz-box-shadow:0 1px 0 #fff;-ms-box-shadow:0 1.3px 0 #fff;-o-box-shadow:0 1.3px 0 #fff;-webkit-box-shadow:0 1.3px 0 #fff;box-shadow:0 1.3px 0 #fff;
border: 1px solid rgba(0,0,0,0.15);
position: absolute;
float: left;
margin: 5px;
line-height: 42px;
height: 40px;
width: 40px;
top: 0;
left: 0;
transition: .5s;
-webkit-transition: .5s;
border-radius: 50%;
-moz-border-radius: 50%;
-webkit-border-radius: 50%;
}
.btn-slide span.title,
.btn-slide span.title-hover {
position: absolute;
left: 80px;
transition: .5s;
-webkit-transition: .5s;
}
.btn-slide span.title-hover {
left: 80px;
opacity: 0;
}