         borderLayer.fillColor = UIColor.clearColor().CGColor
         borderLayer.strokeColor = strokeColor.CGColor
         borderLayer.strokeEnd = 1.0
-        borderLayer.path = UIBezierPath(ovalInRect:CGRectInset(bounds, lineWidth/2, lineWidth/2)).CGPath
+        borderLayer.shouldRasterize = true
+        borderLayer.rasterizationScale = UIScreen.mainScreen().scale
+        borderLayer.contentsScale = UIScreen.mainScreen().scale
+        let cornerRadius = ceil(bounds.height/2)
+        borderLayer.path = UIBezierPath(roundedRect: CGRectInset(bounds, lineWidth/2, lineWidth/2), cornerRadius: cornerRadius).CGPath
         
         return borderLayer
     }

        
        let circleLayer: CALayer = CALayer()
        circleLayer.frame = CGRectMake(CGRectGetMidX(frame) - height/2, 0, height, height)
        circleLayer.cornerRadius = height/2
        circleLayer.backgroundColor = fillColor.CGColor
        
        return circleLayer
    }

        tickBorderLayer.frame = CGRectMake(CGRectGetMidX(containerFrame) - (5*lineWidth)/2.0, CGRectGetMidY(containerFrame), containerFrame.width, containerFrame.height)
        tickBorderLayer.lineWidth = 1
        tickBorderLayer.fillColor = strokeColor.CGColor
        tickBorderLayer.shouldRasterize = true
        tickBorderLayer.rasterizationScale = UIScreen.mainScreen().scale
        tickBorderLayer.contentsScale = UIScreen.mainScreen().scale
        
        let tickPath = UIBezierPath()
        let tickWidth: CGFloat = lineWidth
