Made of high quality fabric and resistant seams. 
	
Its triangular shape goes round the tunnel in a very effective way to keep the tunnel stable even with big dogs. 
	
Velcro-adjustable. It is detachable in two parts for easier carrying, and allows maximum adjust. 
	
Can hold up to 40 lbs in each side. 
	
It´s advised to fill them up with gravel instead of sand.
	
It is recommended 1 bag should be used for each 1 meter of tunnel.