Small Shell Holes 6pc - Small Shell Holes 6pc - Size" 1.5" diameter - The Finished 15mm flexible Field & Trench Works are made with a RTV rubber that that does not continue to shrink after curing. The rubber is also very durable as it will return to its original shape if it becomes bent in storage. The RTV rubber does not continue to shrink after curing and is a great alternative for those with latex allergies. The rubber is also very durable as it will not melt from heat such as direct sunlight or being left in the car. - JR 15mm Flexible Terrain