I use similar to these.
They’re not adjustable at all but sit down flush with the top of your handlebar and weigh nothing. They’re a nice alternative to the Hirschi head-unit grab and keep you UCI compliant on your ride to Lidl.
They use a clamp like a Kalloy uno stem faceplate. The threaded bit in the carbon is flakey so only torque them to ~ 3nm (I think) and go slow, back and forth, small quarter-turns between the two bolts. Then they’re fine.