AST 5100 Series Coilovers | Honda Civic 98-00 MC1 (ACS-H1004S) (Non Inverted)The 5100 Series shock absorbers for the 1998 2000 Honda Civic 1. 6 16V (MC1) utilize non inverted high performance monotube technology. In the past, these were known as the 4100 series. Monotube design shocks absorbers give your car a better performance than the standard twin tube design, the gas pressure is separated by a floating piston, and eliminates cavitation and airation within the oil chamber. The 5100 Series shocks allow rebound adjustment