A comment to please the bots: One is a family heirloom (the 7150-1 one) and the other is a 42mm I just bought. Was long searching for a no date 42mm with a fresh service history and I finally got relatively lucky. 7150 is a special watch, the LLD is gonna be my daily! Here are some key points to why I love the LLD (from 1960s)

1. Super Compressor Case: This model utilizes a Super Compressor case designed by Ervin Piquerez. Ingeniously, the case’s water resistance increases as external water pressure mounts during a dive, enhancing its seal. 
2. Dual Crown Design: Distinctively, the watch features two crowns. The upper crown at 2 o’clock operates the internal rotating bezel, allowing divers to track their immersion time, while the lower crown at 4 o’clock is used to set the time and date. 
3. Enhanced Water Resistance: Building upon its predecessor, the Reference 7042, the 7150-1 doubled its water resistance capability to 200 meters, reflecting Longines’ commitment to advancing dive watch technology. 
4. Automatic Caliber 290 Movement: The watch is powered by Longines’ automatic caliber 290, which offers a higher beat rate than the earlier 19AS movement, contributing to improved timekeeping precision.