There's four different kinds of PowerCache cards for the IIci style cache slot.
-"P30" IIci and IIsi only (has P30 label at the back near the cache connector and should say IIci on the front)
-"P31" adds support for Mac II, IIx, IIcx, LC (likely LCII and CC as well) and SE/30 (P31 label at the back near cache connector and just says "PowerCache" at the front)
-"P33" adds support for Macintosh SE, Classic and LCIII
-"P34" is the same as P33 but with a QFP CPU
The P31 is often referred to as being the IIci version, which is not true. That likely became a thing because of the misinformation spread by Artmix as it did not work in their SE/30 adapter which was a fault of their adapter and not the PowerCache.