Kala Ukulele Machine Heads BK

Very well made from a lightweight but high quality plastic by Graph Tech the inventors of "Tusq" and "Nubone". They were easy to fit. I was travelling at the time, though I did need to borrow a reamer and open out the peg holes by about 0,5 mm to accommodate the new press fit bushings, the old ones tapped out easily.
ADVANTAGES: Superlight compared to the metal (guitar type) originals...maybe 100 grammes lighter, giving much better balance on the sopranino ukulele, and making it possible to focus more on good fingering. I think the tuning ratio is 6:1 and it's so easy to turn the peg just a fraction to get perfect pitch. I was really happily surprised to find them a delight to use. And they hold the string firmly in place. These are geared pegs but the mechanism is cleverly designed and well concealed. And being plastic there is much less concern about damage from moisture. A truly better-than-excellent product.
DOWNSIDES: It's possible that at least one of your old screw holes will need filling and you'll need to make a new one for each peg. And reaming out even 0,5mm requires some care. If you use a tapered reamer (likely) you'll need to make sure you keep the cutting edge at right angles to the face of your ukulele headstock.
Are they worth it? Totally, absolutely, no question!