Hey surfers! So these UP SURF quad fins are pretty legit - they come as a set of 4 fins made from solid fiberglass. The company has been in the surf industry for over ten years, so they definitely know what they're doing. These fins are lightweight but still super responsive and fast, which is exactly what you want when you're catching waves. The quad setup (that's four fins total) really helps with speed in smaller waves, and the two front fins give your board some extra stability. The rear fins have a 4.37 inch base and are 3.62 inches tall, while the front fins have the same 4.37 inch base but are taller at 5.43 inches. They've got this traditional single-sided flat design that lets you really enjoy that speed and freedom on the waves. Oh, and they're compatible with single tab fin boxes - just remember the fin box itself isn't included. The UP SURF team has actually tested these fins themselves to make sure they're durable enough for real surfing. Whether you're just starting out or you've been surfing for years, these quad fins are a solid choice for most wave conditions!