Capacity varies by model and by whether you’re measuring the milk bottle or a collection cup. Typical capacities shown across models range from about 2.5 ounces (≈75 mL) up to about 10.8 ounces (≈320 mL). Check each pump’s product specs for exact bottle or collector volume.

Hands-free or wearable pumps use features that let you pump discreetly inside a bra: soft silicone collection cups or molded collectors that sit in the bra, secure seals to prevent leaks, compact rechargeable or pocket-sized motors, and designs that integrate tubing or internal motors for cordless operation. Product listings typically call out “wearable,” “hands-free,” or “in-bra” capability.

Pumps use three main power approaches: manual/no-power designs (silicone collectors or hand pumps that require no cords or batteries), mains-powered electric pumps (use an AC adapter), and battery/rechargeable wearable pumps (many list a lithium‑ion battery option). Some electric models offer both mains and battery operation.

Common materials include food‑ or medical‑grade silicone (often used for collection cups), various plastics such as polypropylene, and thermoplastic elastomers (TPE). Individual product pages typically specify materials for parts that contact milk.

Common inclusions are breast shields/flanges, milk storage bottles or nipples, connector valves and membranes, power accessories (AC adapter or power cord), and sometimes carrying cases or storage caps. Some electric pump kits also include tubing.

Many electric pumps offer adjustable suction strength and cycle/speed settings plus multiple modes (for example a let‑down mode and an expression mode). Some double pumps provide independent controls for each side so you can set different suction levels simultaneously.