Limar's £104 Pro 104 Ultralight helmet got a good write-up recently from road.cc's Roger Blessed. This 575 Sport Action will sting you for a much more humble £39.99 but still carries over some of the features of the Pro, such as the in-mould construction and the dial adjust headband. That dial makes it a cinch to secure and the L that I tested was a pretty good fit on my (large, round) melon. At 270g it's reasonably light too.
This low-profile lid from Limar is extremely lightweight – 187g, to be precise. That’s even lighter than the manufacturer’s claimed 200g for the large size, and safely inside the ‘so light you can barely feel it’ range. Your highest priority might not be to trim off grams when it comes to protecting your head, but the 104 passes all the safety regs, so who are we to argue?