Butterfly needle sizes: gauge, needle length and tubing length

A butterfly set carries three numbers, not one: gauge, needle length, tubing length. Gauge runs 18 G to 27 G. Tubing runs 3 1/2 in to 12 in, or 10 cm to 30 cm. A fourth thing separates otherwise identical codes — what the tubing ends in.

Every catalogue number, by gauge, needle length and tubing length

1. Nipro's data sheet prints PSV-24-ET with the same description it gives PSV-23-ET — 23 G x 3/4 in (0.6 x 19 mm) — while specifying a different minimum flow rate for each: 5,6 ml/min for PSV-24-ET against 7,8 ml/min for PSV-23-ET. Both the 2018 and the 2020 revision print it that way, and neither resolves it. The row is reproduced as published.
2. BD's brochure prints a needle outer diameter of 1.1 mm for both its 18 G and its 20 G rows — a figure this table does not reproduce. They cannot both be 1.1 mm, and nothing in the brochure settles which is right.
3. Saf-T-Intima is a closed catheter system with a pre-attached extension set, not a steel winged needle. The length above is the catheter; BD publishes no tubing figure for it.

Three numbers that move independently

ICU Medical's Saf-T Wing shows the pattern cleanly. Three gauges from 21 to 25 — two tubing lengths, 6 in and 12 in, and three terminations: none, or a Saf-T Holder (pre-attached or detached). All eighteen combinations carry their own catalogue number. Needle length never moves off 3/4 in. A code that matches on gauge and needle length can still be the wrong box.

Termination is the number nobody prints on the wing

Each manufacturer names the tubing end differently, and the words do not map onto each other. Terumo's Surshield FAQ states the differentiator between its two Surshield lines: "It is the Venoject luer adapter. The luer adapter comes attached already with our blood collection set, while the infusion set has the little cap at the end of the tubing." ICU Medical's Saf-T Holder adds a permanently attached back-end needle and a luer lock. Greiner Bio-One catalogues one needle four ways: bare, with a luer adapter, with a holder, with a blood culture holder. BD's two catalogue columns read Y Adapter and Straight.

Inches and centimetres do not line up

Greiner's tubing runs 10 cm to 30 cm, including a 19 cm option. Nipro publishes 300 mm. Terumo and ICU Medical publish 3 1/2 in, 6 in, 7 in, 8 in and 12 in. Converted, 19 cm is 7.48 in and 30 cm is 11.81 in — so distributor listings restating Greiner's 19 cm as "7 1/2 inch" are rounding, and that figure is not Greiner's. Terumo carries both 7 in and 8 in in the same portfolio: 7 in on the Surshield blood collection sets, 8 in on the two 1/2 in codes, SV25ELF and SV27ELF. Not a typo. Every figure here is tubing alone; no manufacturer states a total set length.

One device, several names

Winged infusion set. Scalp vein set. Winged needle set. Blood collection and infusion set. Terumo Europe glosses its own product "(= Scalp Vein or SV set)", and Nipro's 2018 data sheet calls the item a Winged Needle Set where the 2020 revision of the same reference codes says Scalp Vein Set.

What separates near-identical codes

Terumo's own note: packaging displays SV-BLK codes with an asterisk in place of the dash. The Surshield safety line runs 19 G to 25 G at 3/4 in only — the 18 G, 22 G, 27 G and 1/2 in codes in the plain Surflo line have no safety counterpart. Greiner's 25 G is thinly covered: one bare item, one with a luer adapter, one with a holder, none with a blood culture holder. The 2008 FDA clearance behind the Saf-T line names the sizes in the device title itself, "WITH 21G, 23G, 25G SAF-T WING", filed by Smiths Medical ASD, Inc., whose product ICU Medical publishes today.

Where to buy

One retail listing matches a set above: Terumo Winged Infusion Set 21Gx3/4" | Ultra Thin Wall Needle, 12 Inch Flexible Tube. The title carries all three numbers — 21 G, 3/4 in and 12 in of tubing — which places it against SV-21BLK, the only Terumo code at that combination. Amazon restricts the listing to Business accounts holding a healthcare licence, so it shows no consumer buy box.

Sources

• Terumo Medical Corporation — SURFLO Winged Infusion Sets, product codes
• Terumo Medical Corporation — Surshield Safety Winged Infusion Sets
• Terumo Medical Corporation — Surshield Safety Winged Blood Collection Sets, including the product FAQ
• Terumo Europe NV — Surflo Winged Infusion Set
• ICU Medical, Inc. — Saf-T Wing Blood Collection and Infusion Set
• U.S. Food and Drug Administration — 510(k) premarket notification K081229, applicant Smiths Medical Asd, Inc.
• Greiner Bio-One GmbH — VACUETTE SAFETY Blood Collection Sets brochure, 980157 rev.02 (03.2019 e)
• Nipro Medical Europe — Standard Scalp Vein Set data sheet, 08 Nov 2018
• Nipro Medical Europe — Standard Scalp Vein Set data sheet, 22 Jul 2020
• BD Switzerland Sàrl — BD Saf-T-Intima Safety System brochure, BD-44501 (06/23)

Specifications last verified: 2026-07-31