Strange circle around floating action button noticed in android 4.4?

Question

I have notice a strange shaded circle around every floating action button ,when i install this app in android 4.4. I would highly appreciate for any help. It works fine in version 6,7,and 9 as well.

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<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="105dp"
    android:layout_height="121dp"
    android:layout_alignParentBottom="true"
    android:layout_gravity="right|bottom"
    android:layout_marginRight="8dp"
    android:layout_marginBottom="-1dp"
    android:outlineProvider="none"
    android:scaleType="center"
    android:src="@drawable/alarm01"
    android:visibility="visible"
    app:backgroundTint="#00FFFFFF"
    app:borderWidth="0dp"
    app:elevation="12dp"
    app:rippleColor="@color/shadow_mid_color" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab1"
    android:layout_width="105dp"
    android:layout_height="121dp"
    android:layout_alignParentBottom="true"
    android:layout_gravity="right|bottom"
    android:layout_marginRight="8dp"
    android:layout_marginBottom="-1dp"
    android:outlineProvider="none"
    android:scaleType="center"
    android:src="@drawable/mic01"
    android:visibility="gone"
    app:backgroundTint="#00FFFFFF"
    app:borderWidth="0dp"
    app:elevation="12dp"
    app:rippleColor="?android:attr/colorActivatedHighlight" />

Answer 1

set app:elevation to 0dp.

and if you want to set border to floating action bar, do this:

app:backgroundTintMode="screen"
app:elevation="12dp