Nursi Luna flange sizing kits & pumping essentials

Why the flange tunnel matters more than suction

Every breast pump, whether it plugs into the wall, clips to a waistband or hides inside a bra, meets your body at one point: the flange, also called the breast shield. The wide funnel rests on the breast; the narrow tunnel at its centre is where the nipple moves back and forth with each cycle. That tunnel, not the motor, decides how a session feels.

Pumps leave the factory with 24mm shields because the number sits near the middle of the chart. Yet a large share of mothers measure 13 to 20mm. In a tunnel that is too roomy, the areola is drawn in along with the nipple, rubs against the plastic and swells. Milk moves more slowly, sessions stretch out, and many mothers turn the suction up to compensate — which usually makes the soreness worse.

How flange inserts change a 24mm shield

A flange insert is a soft silicone sleeve that slides inside the tunnel of the shield you already have. It narrows the opening to a smaller size without replacing the shield, the bottle or the pump. Nursi Luna inserts come in 13, 15, 17, 19 and 21mm, so a standard 24mm shield can step down in small, two-millimetre increments until the fit feels right.

Because the insert is liquid silicone rather than rigid plastic, it also adds a cushioned edge where skin meets shield. Mothers often describe the change less as “stronger suction” and more as “it stopped pinching” — and a relaxed body tends to let milk flow more easily.

Measuring at home: the two-to-four millimetre rule

You do not need an appointment to find a starting size. Before a session, place a ruler across the base of the nipple — not the darker areola around it — and read the width in millimetres. Add roughly 2 to 4mm and choose the insert closest to that number. A 16mm nipple, for example, usually begins in a 19mm insert.

Measure again after pumping; the difference shows how much the nipple swells and whether the next size up would be kinder. Many mothers find their left and right sides measure differently, and that sizes shift in the first fortnight, again as supply settles, and sometimes months later. That is the reason every Nursi Luna kit carries two inserts of each size and a silicone nipple ruler, and why the size finder on this page lets you try the arithmetic before you order.

Choosing between our flange sizing kits

The 3-in-1 flange sizing kit is where most mothers begin: ten inserts from 13 to 21mm, a nipple ruler, an IBCLC-written guide and a sponge brush, packed in one of seven case colours. The 8-piece kit keeps the four middle sizes, 15 to 21mm, for mothers who already sit in that range. Our IBCLC-developed 10 or 13 pack adds a more precise ruler and a guide for tracking changes over the months.

If you are packing for the hospital, the bundles save a second order: one pairs the insert kit with 60 breast milk storage bags, another with 50 individually wrapped nursing pads. And once the ruler has settled on a number, single-size packs of four 15mm, 19mm or 21mm inserts come with a carry case, so there is always a clean pair waiting.

Which pumps the inserts fit

Nursi Luna inserts are made for 24mm shields and sit in most 24mm shields from electric, wearable and manual pumps. Mothers tell us they use them with Medela, Spectra, BabyBuddha and Momcozy shields. They are not designed for 27 or 28mm shields, and they will not help if your measurement calls for a size larger than 24mm — in that case, the shield itself needs to change.

Care, cleaning and when to replace

Wash inserts after every session in warm, soapy water with the sponge brush from the kit, run them on the top rack of the dishwasher, or boil and steam them with the rest of your pump parts. Silicone softens slowly with use, so we suggest a fresh pair every one to two months, or sooner if the seal feels loose.

The same rule of wear applies to the rest of the milk path. Duckbill valves, membranes and backflow protectors stretch long before a motor fails; our replacement sets for Spectra S1, S2 and 9 Plus pumps restore suction for a fraction of the cost of a new pump.

Everything else beside the nursing chair

Around the kits sit the small things that make the first months calmer: a hands-free wearable breast pump with massage and expression modes and its own set of inserts, silicone colostrum collectors for the very first drops, a soft ruler and tape for measuring, and fragrance-free tablets for the bottle washer that runs while you sleep. Each one earns its place the same way — by making pumping a little softer, which is what Nursi Luna was named for: the hours under the moon that only you and the baby see.