The 98-6 is a 6-inch machinist level featuring a ground and graduated main vial with a cross test vial. It does not include a case. The base has an involute groove running its length, providing a secure seat for round work. The vials are adjustable for precise positioning and are housed in a satin-finished brass tube with a friction-fit cover to prevent damage. The main vials have graduations of approximately 80 to 90 seconds. Ideal for test and measurement applications.