ZrO2 full ceramic ball bearings are best used at low speeds. For higher speeds or continuous rotation over long periods, never rusty and corrosion resistance.

Full ceramic bearings made from ZrO2 to handle extreme temperatures and highly corrosive environments. 

623CE Zirconia Ceramic Ball Bearing 3x10x4mm ABEC9 High Performance Ceramic Bearing for Fishing Reels features:

Model: 623CE

Size: 3x10x4mm ceramic bearing

Ring Material: ZrO2 full ceramic

Ball Material: ZrO2 full ceramic

Cage: PEEK/PTFE

Lube: Dry lube

Sealed: Open

Package: Individual white box

Features: This size 3x10x4mm ceramic ball bearing is most common size bearing in all baitcasting fishing reels is white Zro2 Zirconia Ceramic Bearing, never rusty, can contact seawater, saltwater directly.

623CE Full Ceramic Bearings pictures as below:

Zirconia Oxide Ball (ZrO2)full  ceramic bearings  has the highest strength and toughness at room temperature of all the advanced. High quality full ceramic bearing are suitable for use in many specialty applications seeking to reduce overall weight and rolling resistance.

Zirconia (ZrO2) is a cost-effective alternative to Si3N4. It also has the advantage that the thermal expansion is similar to that of steel.  the rings in full ceramic bearings are typically manufactured from silicon nitride, Si3N4, or zirconia, ZrO2. Retainers in full ceramic bearings are typically made from high-performance plastics such as PEEK , PTFE or nylon.  Full complement versions are also available.

Benefits Of Full Ceramic Bearings: resistant to acid, salt and water, and blood, non-magnetic, lower coefficient of friction, resistant to electricity, corrosion-resistant, lighter, smoother and stiffer.

Full ceramic ball bearing applications:

Applications For Full Ceramic Bearings: MRI equipment, vacuum environments, semiconductor manufacturing, radiotherapy, food processing industrie, any extreme environment requiring non-corrosive, non-conductive or non-magnetic bearings.

Related Hybrid ceramic ball bearing popular sizes as following:

Ceramic Ball Bearing bore 2mm:  2x5x2mm, 2x5x2.5mm, 2x6x2.5mm, 2.5x6x...

Ceramic Ball Bearing bore 3mm: 3x6x2mm, 3x6x2.5mm, 3x7x3mm, 3x8x2.5mm, 3x8x3mm, 3x8x4mm, 3x10x4mm, 3x11x4mm

Ceramic Ball Bearing bore 4mm: 4x7x2mm 4x7x2.5mm, 4x8x2mm, 4x8x3mm,4x10x4mm, 4x11x4mm,4x13x5mm

Ceramic Ball Bearing bore 5mm: 5x8x2mm, 5x8x2.5mm, 5x9x3mm, 5x10x3mm, 5x10x4mm, 5x11x3mm, 5x11x4mm, 5x13x4mm

Ceramic Ball Bearing bore 6mm: 6x10x2.5mm, 6x10x2.5mm, 6x10x3mm, 6x12x4mm, 6x13x5mm, 6x15x5mm, 6x19x6mm

Ceramic Ball Bearing bore 7mm:7x11x3mm, 7x14x3.5mm, 7x14x5mm, 7x17x5mm

Ceramic Ball Bearing bore 8mm: 8x12x2.5mm, 8x12x3.5mm,8x14x4mm, 8x16x5mm

Ceramic Ball Bearing bore 9mm:  9x17x5mm, 9x20x5mm

Ceramic Ball Bearing bore 10mm: 10x15x4mm, 10x19x5mm, 10x20x5mm

Ceramic Ball Bearing bore 12mm: 12x18x4mm

Ceramic Ball Bearing bore 15mm: 15x21x5mm....

Inch/imperial sizes  Ceramic ball bearing : SR2C-2OS 1/8" x 3/8" x 5/32, SR156C-2OS 3/16" x 5/16" x 1/8, SR166C-2OS 3/16 x 3/8 x 1/8, SR168C-2OS 1/4"x3/8"x1/8..