The Rob Allen Couta mask has been around for a long time and with good reason, it fits majority of faces and is super comfortable. The adjustable straps with easy squeeze side clips allows for a perfect fit every time. With the single tempered glass lens you have high visibility and it is extremely low volume. Being low volume means that there is less air inside the mask when being worn. When heading underwater, you need to equalize, this means you need to equalize the air inside your mask to prevent for mask squeeze. When on scuba diving, this is easier as we have spare air to use from our tanks, however when spearfishing, you are on breathe hold so you need less air in your mask so you dont use up too much breathe equalizing. This is why the spearfishing masks are low volume.