8pcs of wooden wedges to re-tighten the canvas

If the stretched canvas becomes loose, we can use the wooden

wedges to re-tighten the canvas:

1) Remove the staples at the 4 corners on the back of the

stetched canvas by screwdriver.

2) Insert the wedges into the 4 corners as attached picture.

3) Hammer the wedges lightly,enabling the bars extending

outward, until the canvas arere-tight enough.