Observation
The observation bunkers were built in such a way that a good view at the shoreline was garanteed, so some of them are directly at the beach, others lie on hills more inland. One observationbunker could manage more than one battery.
A derivation of the 666 has a close combat room (Nahkampfscharte) and the door, which leads to the cupola, is assymetrical placed in the wall of the room for personnel. Some call this bunker a 666Sk. In 1997 we have found this bunkertype in St Nazaire and in 2003 one in Kerviec, Lorient. German archives give two times a 637a built in Lorient: Lo 045 (Kervaugam) and Lo 064 (Kerviec). The internal layout of the regular 637 fits the observation bunker found at Kerviec. The "hood" is replaced by a cupola. Measurements were taken by others and show that the so-called 666Sks in Lorient and St Nazaire are identical. Many colleges gave information, they made it possible to make our conclusion that the 666Sk is the 637a.
On our tour to Lorient in 2006 we visited the known to us locations for artillery observers.
| Location | Lo nr | possible type (sources) | Type found | Battery |
| Bas Pouldu | Lo xxx | 120 | not found | Kerhop |
| Villeneuve-Ellé | Lo 020 | 666Sk | 637a | Coat Cant |
| Guidel Sémaphore | Lo 023 | 120 | 120 | Croëz-Hent |
| Höhe 40 | Lo xxx | 143, 120, 666Sk (637a) | 120 | Lann er Roc'h? |
| Höhe 40 | Lo xxx | 613 | 613 | Pen Hoat/Keraude? |
| Höhe 40 | Lo xxx | 665 | 665 (infantery observer for 633) | Höhe 40 |
| Locmiquel-Mène | Lo 027 | 665 | 637a | unknown |
| Locmiquel-Mène | Lo 027 | 613 | not found | unknown |
| Fort Blocqué | Lo 028 | 613 or 666(Sk) | 637a | Kerchaton |
| Kervaugam | Lo 045 | 665 | 665 (infantery observer for 633) | Kervaugam |
| Kervaugam | Lo 045 | 637a | not found | unknown |
| Kerviec | Lo 064 | 666Sk | 637a | unknown |