Longines Caliber L898.5 Watch Movement

Brand	Longines
Caliber Number	L898.5
In-House?	No
Exclusive?	Yes
Base Caliber	ETA A31.L01 (ETA 2892A2)
Movement Type	Automatic, self-winding mechanical, chronograph
COSC?	No
Lignes	11.5”’
Diameter	25.6mm
Jewels	37
Power Reserve	59 hours
Beat Rate / Frequency	28,800 bph / 4 Hz
Lift Angle	51 degrees (unconfirmed!)
Shock System	Nivashock
Balance Spring	Silicium (silicon)
Rotor Style	Ball bearing system
Rotor Winding Direction	Bi-Directional
Hand-Windable?	Yes
Hand-Count	6
Chronograph Layout	3-6-9
Chronograph Type	Modular
Features	Central hours; central minutes; central chronograph seconds; small running seconds subdial at 3:00; 30 minutes chronograph counter at 9:00; 12 hours chrono counter at 6:00
Hacking Seconds?	Yes
Country of Manufacture	Switzerland, Swiss made (V8)
Known Models	Conquest 2023 Chronograph (Ref: L3.835.4.02.6, L3.835.4.02.9, L3.835.4.32.6, L3.835.4.32.9, L3.835.4.52.6, L3.835.4.72.6, L3.835.4.92.6, L3.835.4.98.6, L3.835.4.98.9) (Add your watch in the comments below…)

Longines caliber L898.5 is an automatic chronograph watch movement. It is Swiss made with 37 jewels and features a silicon anti-magnetic balance spring.

This calibre is found in the 42mm Longines Conquest Chronograph models introduced in 2023 and 2024 (retail price $3,750 USD).

Base Caliber:

Although this movement is produced by ETA (Swatch Group) and based on the ETA caliber A31.L01, the L898.5 is exclusive to Longines.

The A31 series itself is based on the ETA 2892A2, making this a modular chronograph movement – in other words, the chronograph complication is a module on top. This also explains why the movement does not resemble what many enthusiasts are used to when looking at it through the exhibition caseback.

Silicon Balance-Spring:

As mentioned above, one of the Longines caliber L898.5’s notable features is its use of a silicon balance-spring (hairspring). With so many magnets being used in modern everyday accessories and appliances, magnetism is one of the most common threats to the accuracy and functionality of a watch. Using silicon for the balance-spring makes it antimagnetic. As Longines puts it:

“Silicon is lightweight material which is resistant to corrosion and it unaffected by normal temperature variations, magnetic fields, and atmospheric pressure. Its unique properties enhance a watch’s accuracy and longevity.” –source

To reinforce the importance of magnetic resistance in a watch and its impact on a timepiece’s overall performance, Longines has extended their manufacturer’s warranty to 5 years on all watches with a silicon balance-spring (announced 9/2020 – source).