Ok, so I just got mine today and tested it on my Galvatron. There's no secure grip on the inside but with the way it's designed it won't fall off easily. It does wiggle loosely on his head though. Over all it looks too big for his head. I feel flattening or removing the top and maybe sanding down the top sides would help this a lot. I don't mean the horns but the actual helmet part. I'll probably make these changes myself but I just wanted to leave some feedback. Still it came out fantastic, just need some paint to match the plastic.