Large 45g chalk capacity to reduce refilling times. Rubber over moulded case for strength and better grip. High impact ABS case for durability. Sliding door for quick and easy refill. Metal crank folds into the case for ease of storage. Stainless steel end hook for added durability and rust prevention. Patented chalk view window to see exactly how much chalk you have left. 3.5 to 1 gear ratio - rewinds 3x faster. Can be used vertically as a plumb bob.