Sorry Phil that website is wrong...
Although it is possible that an uploading error might occur, I believe that the present information found in the StrobeFinder to be consistent with that published by the respective manufacturers. I would also like to add that prior to originally publishing the database, Ike Brigham verified all Ikelite specifications, including the DS 125. And Mark Rupert verified all INON data, including the Z220.
As stated, information found in the StrobeFinder comes directly from published specifications provided by the manufacturer. There exists only two exceptions to this rule. The underwater weight of the DS 125 (NiCAD battery pack) was calculated independently and verified by Ike Brigham. The newly released S&S YS 250Pro Watt second rating was measured by a respected independent test facility and can be found by clicking the "notes" link (250 Ws).
For uniformity, all Guide Numbers listed in the StrobeFinder are posted in Meters, ISO 100. Some manufacturers provide both top side and underwater Gn's. Most however provide only the top side guide number.
Not all manufacturers list Watt second ratings.
Strobes are not equally efficient at taking advantage of their stored energy. Strobes by design also use their energy storage differently (some spread the light more whereas some focus their energy more "precisely").
Ikelite strobes tends to derive their model names from their approximate Watt Second rating (DS 51 = 50 Ws, DS 200 = 200 Ws, etc). INON strobes tend to derive their model names from their top side guide number rating, listed in meters (ISO 100). For instance, the D 180 has a top side GN of 18 (meters, ISO 100) and all versions of the D 2000 (S, W, Wn, etc) are rated through air by INON at GN 20 (M, ISO 100). Z-240 =Gn 24.......and so on......
hth,
b