Treu but I'v noticed with ED shaped lamps the hole at the tip of a 250 watt lamp is sometimes slightly larger than a 175's. But honestly it may be 175 watt. Never truly know without a nema label. Hey since we'r on the nema head subject I would like to e-mail you a pic of one I just installed in my yard it's an AEL 11-S-RN-120-BA and a Utility Metals 6 foot 1-1/4 bracket with underbrace. Let me know what you think. I added the nema label because I though your's looked realy good.
Hmm, I always thought the size of the hole at the tip of ED shaped lamps varied among different lamp companies. I guess one way to tell if the ballast is visible is to look at the ballast itself. A 250w ballast should be noticeably bigger than a 175w.
this probably has a FP lens since those look pretty close to glass until they start yellowing (well, the poly ones at least). This is probably 175W. Anyhow, I have a 175W clear Sylvania merc and a 250W /DX sylvania merc and both have the same sized dimple.