Bonnel spring frames made at 80-170 mm range are put through heat treatment processes to prevent sagging.  Manufacturing wire with width ranging from 1,90 mm to 2,45 mm and spring with 4-5-6 spin springs to various height specifications is possible.

Boyçelik made bonnel frames are;
• Classic and best known spring system.
• Comfortable, durable and economic.
• Manufactured in varying wire and spring diameters.
• Provide long term use and comfort advantage thanks to spring fatigue and annealing processes during production.