The term Co-Axial represents a specialized watch escapement exclusive to Omega that was developed in 1970 by British horologist and watchmaker George Daniels. The Swiss Lever escapement has been the standard in horology for hundreds of years. The escapement provides the release of energy from the mainspring to the going train that further controls the function of the moving parts that measure time and other complications. The Swiss lever, although the mainstay in the industry, has the capability to be strong on energy conservation but needs considerable lubrication between the impulse pallet and the escape wheel teeth due to sliding friction. This causes considerable wear on the lubrication over time and may cause wear on the pallet or escape wheel. Because of this, regular service (4–5 years) is recommended to clean, lubricate, and possibly replace parts. With the co-axial escapement, the impulse is done with a push to the jewels rather than a sliding fashion. In this design the work is divided between two major wheels of the escapement. Daniels brought his desire to industrialize his escapement to many Swiss manufacturers and he was ultimately denied. Omega in 1999 took on Daniels design with the insight of Nicolas Hayek who saw Omega as a brand of innovation and creativity who would rise to the top of the Swiss horological spectrum with the production of the co-axial escapement. He was right and Omega is one of the largest Swiss manufacturers and the second largest producer of COSC Officially Certified Chronometers, next to Rolex with Breitling being third, with every one of their movements COSC chronometers. The first co-axial movement to be brought to the public was the Omega cal. 2500, with different variations being listed as A,B,C, and D. This movement was built from the Omega "in-family" cal. 1120 (finished chronometer grade ETA 2892-A with two extra jewels) A, B, and C are similar two tier co-axial movements, but C is the first version to solve certain problems prevalent in A and B. For example, the vibrations per hour were originally 28,800 (standard for most Swiss watches with Swiss Lever Escapements) but later lowered to 25,200 (7 vs 8 v beats a second). This change was noted that it was the optimal working vibration of the movement and may contribute to lower service intervals. The Co-axial D variation was made to allow for an even more efficient 3 tier escapement. This development of technology helped the company innovate the 8400 (no date)/8500(w/date complication)/9300 (chronograph) three tier in-house movements. The co-axial D variation is still made specifically for the Omega Diver 300m co-axial. The Diver 300m, a watch produced since 1993 has a certain shape and size that is characteristic of this watch, the 2500 is slender enough to keep the case shape and size proportionate on the Diver 300m (also known as the SMP).