i am thinking about buying this ozone c4 used from a guy its a seven meter i am trading my rebel 7 meter for it and he said it would be less powerfull than my rebel is this true i way like 125 will this be enought kite for me and is it a powerfull kite

An Ozone C4 is less powerful than a Rebel, size for size.
Will it be enough kite for you if you weigh 125 pounds?
You did not say what wind range you want to fly in.
Why is your Rebel not working for you?
I would rather have a C4 than a Rebel, for what it is worth.

Correct spelling and some punctuation make it much easier to communicate.

I've an 8m C4 2011 and it covers me from anything from low 20s up to 30 knots at about 155 pounds on a 130.
At 125 pounds I reckon you'd be ok on a 7m for a similar wind range on a similar size board, bigger board you will get out in a couple of knots less. You'll need something bigger for covering the low to high teens though.

C4 has an ok low-end (not great) but excellent high-end, so when comparing to deltas I'd say it roughly sizes 1 m2 smaller, so a 7m C4 would be close in low-end to a 6m rebel.

Size of your gear, weight and wind range are key but technique is nearly as important when at the limits of your range, and you'll need to work the C4 more than a rebel to eek out that last bit of power.

Lots of generalisations above that should help, but the only way to know for sure is to test it out and see how you get on.

I have an Ozone C4 2012 in 8m and i think the C4 has a great low end.
I weigh like 50kg (110 pounds) and I can kite with the 8m in 10-12knots (just cruising, no big jumps) and I can kite with it till 30 knots.
The C4 2011 and 2012 have 3 knots on the back lines just above your bar.
If you are going out in low winds, you have to tie your front lines on the first knot, in medium winds on the knot in the middle and in high winds on the 3rd knot. But I don't know the difference between the 2011 and 2012, because I only have flown with a 2012 C4.
But I think you should buy an 8m instead of an 7m to have the same range as a Rebel 7m.

Fair dues getting going on an 8m in 10 knots no matter what weight you are. I've an 11m so never bother with the 8m in less than 20 knots, at a push I'd be able to keep upwind on the 8m around 16/17 knots.

Have you it set to wakestyle or free-ride and what bar setting to you have it on? I've both kites in the lightest/fastest setting (closest to the tips) and on wakestyle (2nd knot out), I must have a play around to see what sort of effect it has on low-end.

You don't have to believe me, but this holiday in Viana (Portugal) we had a day of 10-12 knots.
And I could kite with the 8m but as I said only cruising and doing some backrolls and stuff (no big jumps). I could just stay upwind but I had to steer my kite in 8's sometimes.
And the same day my dad (80kg) couldn't stay upwind with his 11m (ozone sport+).
I had it on the nearest knot to the bar (maximum power) and on the free-ride setting and lightest bar setting/fastest steering. But I weigh 50kg and you weigh 70kg so that's a big difference. And the Ozone C4 2012 seems to have a better low end than the 2011 according to the reviews and guys who have kited with both.

The next day the wind was better and was blowing around 28-32 knots and I was on my 8m again.
This time I had in on the 3rd knot, on freeride setting and the depower was half way and sometimes I was a bit overpowered but I could hold it. But I have ordered a 5m because over the 30 knots I had to depower the too much and then the kite became too slow.

PS: I don't know the 2011 has the 3 knots just above the bar. But these 3 knots are another 15 or 20cm of depower. The first knot above the bar is maximum power, the 2nd medium power and the 3rd is the least power. So if you play around with these knots you have to feel the difference.

im dislexic