Hayabusa S4 Boxing Gloves review

The S4 uses a single hook-and-loop strap, unlike the T3-family gloves in this library that use two interlocking straps. The current US product page describes single-layer foam splinting at the wrist and injection-molded knuckle foam. It lists 10, 12, 14, and 16 oz versions, with letter sizes shown alongside the ounce choices. The company presents it as a beginner glove for bag work, drills, and fitness boxing. That gives a shopper a clear starting point, but not enough evidence to call it a universal sparring choice.

This is an evidence-led assessment of the published S4, not a trial. I have not worn it, timed its closure, measured the pocket, or tested the padding. Comfort and hand protection depend on fit and technique as well as the material names on a page.

Keep the S4 model identity exact

Hayabusa’s boxing-glove collection also lists S4 Leather, S4 Youth, S4 Youth Epic, and S4 Lace Up. Those names are not interchangeable with the standard S4 reviewed here. The standard product page identifies PU engineered leather, a single strap, nylon lining, and a size selector that maps XS to 10 oz, S to 12 oz, M to 14 oz, and L to 16 oz. A seller listing that says only “S4” does not establish which of those editions or sizes is being offered.

Use the ounce figure to identify the glove-weight option, not your hand size. Check the manufacturer’s hand-size guide and try the glove over the wraps you intend to use. The letter-size mapping is helpful as a clue, but it cannot tell us whether every hand shape in a given size will feel comfortable or secure.

A single strap and a single-layer splint

S4’s one hook-and-loop strap is a straightforward arrangement to understand: wrap your hand, place it into the glove, and close the strap. Compared with the T3’s interlocking dual straps, it has fewer closure pieces to position. That is a mechanical observation, not a measured claim that it takes less time or will suit every user. A single strap may also give you fewer places to tune the closure around your wrist.

The product page calls the S4 support a single layer of foam splinting. Its knuckle protection is injection-molded foam. That is different from T3’s four Fusion splints and multi-layer foam, so a buyer who is comparing the two should focus on those actual structures. The public specifications do not tell us how stiff either design feels, whether the S4 suits a history of wrist pain, or whether the T3 will fit better. If you have pain or an injury, choose with a qualified coach or clinician rather than assuming one feature will solve it.

Where the published use case is strongest

Hayabusa calls the S4 a beginner glove and describes bag work, drills, fitness classes, boxing, Muay Thai, and kickboxing. It is a plausible candidate for a new fitness-boxing shopper who wants a conventional closed-thumb glove and a set of listed weights up to 16 oz. The page does not give a specific S4 sparring recommendation, size rule, or gym protocol. That omission is not proof the glove cannot be used in sparring; it means I would not match it to a sparring request on the strength of this page alone.

For pad sessions, a shopper should distinguish general “drills” from the exact activity their coach has in mind. The S4 page emphasizes bag work and drills but does not publish a weight-by-weight table like the T3 page. Ask the gym about its training gloves and sparring requirements before treating this as a one-pair solution. In the current comparison, the T3 has explicit 14–18 oz sparring guidance; the S4 does not.

Materials and small design details

The listed shell is PU engineered leather, the lining is nylon, and the extras include an attached thumb, aerated mesh palm, foam grip bar, and microfiber thumb intended for wiping sweat. These are manufacturer-stated materials and features. They are not evidence of how breathable the glove will feel after rounds, how well it dries between sessions, or how the fabric holds up after repeated cleaning. Follow the maker’s current care instructions rather than improvising with heat or harsh cleaners.

At the time checked, the public page showed a range of colors. The review image is a white S4 product reference only; it does not establish the precise shade, stitching, or package in a seller’s stock. Verify the color and the exact ounce/letter-size combination in the live offer.

Who should shortlist it—and what to verify

Consider the S4 when a beginner wants one strap, a mid-range weight selection, and a manufacturer-described bag-and-drill use. Pause if you require the four-splint dual closure in T3, need a documented sparring recommendation, or cannot determine how your wrapped hand fits the pocket. The main tradeoff is not simply “less expensive versus more expensive”; prices and offers change, while the construction difference is stable enough to compare.

Before ordering, check four things: the seller has the standard S4 rather than a similarly named variant; your required glove weight is the one in the listing; your gym accepts the model and weight for the session; and the return policy allows a fit check if the glove is unsuitable. For any sparring use, get explicit confirmation from your coach. “Beginner” is Hayabusa’s product description, not a substitute for those checks.

What the available evidence leaves open

I have not worn or tested S4. The manufacturer page does not publish measured weight tolerances, detailed internal dimensions, tested lifespan, a sparring-specific use table, or independent comparative impact data. No fit verdict can be made for an individual hand from a product name or ounce label. The useful conclusion is narrower: S4’s published construction is a single-strap, single-layer foam-splint design with injection-molded knuckle foam and listed 10–16 oz versions. That is enough to compare its intended routine with the products in this library, but not enough to promise comfort or injury protection.