Spark scooters

[ETsmum]

Opinions please. DS would dearly like to have a spark scooter (8 in a couple of months). I fear I may be being all pfb about him, but have concerns over the sparks and him setting fire to stuff (will use in local park). Also, does anyone know how long the cartridge thingamys last - wouldn't want to buy if they need replacing all the time.

I've refused to buy one of these, I'm sure they're perfectly safe but I refuse to keep shelling out for new sparks as I'm sure the cartridges won't last long.

You may be more generous than me

We have one for DS (6). Bought it in November last year for his birthday and we have yet to replace the cartridge - it comes with a spare (and he was told that any extra cartridges would have to be as a future present).
Yes, he is way below the age recommendation but has excellent balance from riding his bike and is a very sensible six-year-old. We talked about the sparks and how he has to be careful with them - but to be honest they'd only ever work on concrete and extinguish pretty much immediately. I was also hesitant about getting one (he is also a pfb!) but he does love it, gets a lot of use out of it and it really did boost his confidence at a relatively difficult time at school.