Outboard crossover? Why not?

Many thanks for all that. It is a price of not really paying attention on a purchase!
As Erik says, the non existence of an internal crossover may not be stated on the back, so what indications can I look for that I have or have not?
Surely jumping can do less damage (Tim thinks so whatever internals??) in any circumstances than triamping, if that is what it is called.? For those who do triamp do they really prefer all those speaker cables?

I am a BIG fan of not using speakers with crossovers inside them.  I use an active crossover (DBX) and it is between my preamp and amps, so my amps actually see my speakers, directly, not my crossover.  When you use internal crossovers, your amps never see the drivers, just the crossover.  

@tatyan69

You run the risk of very easily blowing your tweeter and watching it turn ballistic unless you know what's going on for sure. There's no "less" damage here, either is as risky.

If you have a multi-meter, connect it to the tweeter section. It should, over time, read infinite resistance.

If you get a number between 3 and 10, and it doesn't change after a minute, you don't have a crossover. :)

Of course, you could just take a driver or the panel off and look.

@tatyan69    If you don't have a separate box from the speaker,  the speaker has internal crossovers... You would know if your amp had an electronic crossover to adjust frequency... Jump away,  you will be fine....

The seller included an external crossover box (with instructions - good grief!) so  I suppose all the indications are that I do not have internals. It seems I will have to put these as rears unless I invest in a superior multichanel amp, which makes the whole thing so heavy going + all the extra speaker cables. They seem to however be very pleasant indeed speakers from listening to the ones with internal crossovers, It just makes listening so much more complicated having to sit down and read a manual first. I though those days were over! I am taking them all one at a time (odd shaped luggage at 23kg) to my home in Ukraine so I will have time to read up there, as there is not much to do in Ukraine!