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Insulin Syringes 31G, 0.5 mL (100-count)
The workhorse: a very thin 31-gauge needle on a barrel marked in units (0 to 50).
- 31G
- U-100
- 0.5 mL
- 0–50 units
At a glance
Gauge31GNeedle thickness. A higher number is a thinner needle: 31G is thinner than 30G. Glossary
Capacity0.5 mLHow much liquid the barrel holds. Smaller barrels have more space between the lines, so small amounts are easier to read. Glossary
MarkingsU-100U-100 means 100 units to the millilitre, so one unit is 0.01 mL. A mL scale is marked in tenths. Glossary
Smallest line1 unitWhat one line on the barrel is worth. Half-unit lines let you read 0.005 mL; a 1 mL syringe is usually marked in 2-unit steps. Glossary
Needle length8 mmLength of the needle. 4–8 mm is the usual range for under-the-skin use; longer is for muscle. Glossary
Needle connectionFixed needleFixed means the needle is built in (least dead space). Luer-lock screws on and cannot pop off. Luer-slip pushes on. Glossary
Needle includedYes
TipsharpBlunt tips draw liquid from a vial without being able to go through skin; they are for mixing and drawing up.
Dead spacelowLiquid left in the hub after the plunger bottoms out. Fixed-needle insulin syringes have almost none. Glossary
PriceBudgetRough position within its category, not a live price: budget is the cheapest sensible option, premium costs more for a reason the page explains.
TravelCarry-on friendlyWhether it is practical to fly with: carry-on means it goes through security without fuss.
SterileYesIndividually sealed and sterile until opened. Anything that touches the inside of a vial or your skin should be.
Pack100How many you get. Check this against the photo; Amazon listings often show ten and ship one.
ReusableNo
Amazon listing checked 2026-09-03: listing active and matches this description. Prices are not checked.
Same thing, different spec
Why you’d want it: The most popular all-around size for small, precise doses. Start here.
Picking tip: Confirm the listing says U-100 and that syringes come individually wrapped, not loose in a bag. Barrel colour is cosmetic — brands use it to tell their own sizes apart, so match the numbers, not the colour.
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