Standard spiral materials include bronze, steel, stainless steel, beryllium copper, Monel, and Ni-Span C. Spans as low as 10 PSI (69 kPa) are available for positive, negative, or compound ranges. The various manufacturers use different break points between the spiral and the helical elements. Some start using helical elements at above 200 PSI (1.4 MPa) spans; others stay with the spiral element up to 4,000 PSI (27 MPa) and higher. Unflattened, heavy-wall, spiral tube springs that detect pressures up to 100,000 PSIG (690 MPa) are also available in direct indicators.