Stop buying those universal kits, they're a gamble. I learned the hard way after killing a MacBook Air with a cheap adapter. Now I only use OEM chargers or reputable brands like Anker for universal needs. Keep a few common charger tips in your kit instead. It costs more upfront but saves you from eating repair bills later.
Wait, you really fried a MacBook with one? I mean, maybe anthony72 hasn't had it happen yet, but I've seen those cheap adapters get way too hot. It's not just about the wrong tip, the power delivery can be totally wrong.