Hayabusa S4 Leather Boxing Gloves review

S4 Leather is a separately named Hayabusa model, not just a brown or black finish of the standard S4. Its page identifies a genuine-leather shell, a single hook-and-loop strap, one wrist splint, and injection-molded knuckle foam. The available selector covers 10, 12, 14, and 16 oz. That gives a buyer several familiar ounce choices, but the listing does not say which size to use for every session or label the leather as full-grain.

This is a review of published product information, not a wear test. I have not put the glove on, tested its impact, measured its pocket or timed its closure. Construction names help distinguish the model; they do not establish how it will fit an individual hand, how much protection it provides, or how long it lasts.

Keep the S4 editions separate

Hayabusa lists standard S4, S4 Leather, S4 Youth, S4 Youth Epic, and S4 Lace Up as distinct product names. The standard S4 page describes a PU-engineered-leather exterior and single-layer foam splinting. S4 Leather instead says genuine leather and “single splint.” The Leather page does not state a grain grade or say that its wrist splint is the same foam construction as standard S4. It would be easy to assume that the family shares every internal component, but the evidence here supports only the features stated on this exact product page.

The name also matters when checking an offer. A seller may shorten a title to “S4” or group multiple colorways together. Before ordering, confirm that the item is the Leather edition, then check its color and selected ounce weight in the cart. The official image shown here is black with a visible 14 oz marker; that photo represents the model and color, not a claim that the page only offers 14 oz.

One strap, one splint, injection-molded foam

The page specifies a single hook-and-loop strap. Compared with a glove that uses interlocking straps, this is a simpler closure layout to understand: wrap the hand, seat it inside the glove, then close the cuff. That is a description of the mechanism, not a measured claim that it is faster or that it will secure every wrist. The page calls the wrist support a single splint but does not give a layer count or a foam specification for that piece, so the matcher does not treat it as a confirmed single-layer foam splint.

For the knuckles, Hayabusa names injection-molded foam. That is a more specific construction label than the product page's general claims about protection, but it does not say how a buyer's knuckles will feel or establish impact testing. The gloves also have an attached thumb, a microfiber thumb described for wiping away sweat, a perforated palm, an ergonomic thumb position, and a foam grip bar. A shopper who likes these details should still check whether the interior space and thumb angle work with their hand and wraps.

Where its published use case fits

Hayabusa positions S4 Leather for beginning boxers and fitness enthusiasts and specifically names heavy-bag work, drills, and intense training. The product description also mentions boxing, Muay Thai, and kickboxing. In the finder, the explicit heavy-bag option is supported, but broad “drills” language is not silently converted into pad work, partner drills, or sparring. The product page does not offer a weight-by-session table or a sparring-specific recommendation.

That distinction is useful if you are buying a single pair for a gym with strict rules. A 16 oz selector entry is not, on its own, proof that S4 Leather is the gym's approved sparring glove; the page does not connect that size to sparring. Ask your coach what weight and glove type the class requires. For bag sessions, compare the model's listed weight with your routine and hand fit rather than assuming a heavier glove is always more suitable.

Genuine leather is not a grain grade

The shell description is “100% genuine leather.” It does not say full-grain, top-grain, or another grade. A buyer who specifically wants full-grain leather should not read that more detailed attribute into this listing. This is an important difference from products whose pages name their grain type; the finder leaves S4 Leather out of the full-grain shortlist because the page does not verify it.

The lining is described as soft nylon. Hayabusa also identifies a pre-curved interior and natural hand positioning. Those are useful clues about intended shape, not a fitting result. The product page supplies no internal circumference or measured finger-pocket dimensions. If your hands are unusually broad, if you wear thick wraps, or if you have a history of wrist problems, ask the gym for guidance and make a return-aware fit check before committing.

What to compare and verify

Standard S4 is the closer comparison if you want a single-strap beginner model but prefer a documented PU shell and a page that explicitly says single-layer foam splinting. S4 Leather is the relevant variant if the genuine-leather construction is important, while its grain grade remains unspecified. E1 offers injection-molded knuckle foam too, but it uses a single stretch strap and has a 16 oz-and-up sparring statement; T3 publishes a different Dual-X/four-splint construction and more explicit weight/use pairings. Those are documented contrasts, not proof that one design feels better.

Before purchase, verify four things: the exact S4 Leather title rather than another S4 edition; the selected color and ounce option; your gym's approval for the planned session; and fit over the wraps you intend to wear. Keep the maker's leather-care instructions in mind and do not assume a synthetic-care routine applies. The practical conclusion is narrow: this is the genuine-leather S4 option with one strap, a single splint, injection-molded knuckle foam, and a 10–16 oz selector. The public record does not settle individual fit, grain grade, or sparring suitability.