Full Ceramic (ZrO2) Bearings. (Set of 2, different sizes.) * Other sizes are also available. * A small discount will be offered for multiple purchases. ↓ Specifications: [Palm Cup Side] Size Standard: 623 (also known as 1030) Outer Diameter: 10mm Inner Diameter: 3mm Thickness: 4mm [Spool Shaft (Handle Cup) Side] Size Standard: 693 (also known as 830) Outer Diameter: 8mm Inner Diameter: 3mm Thickness: 4mm Examples of compatible reels: 22 Silver Creek AIR TW Stream Custom Alphas AIR TW (AIR TW only compatible with AIR BFS) 19 Alphas CT SV 19 Millionaire CT SV Alphas SV Alphas Finesse Custom 20 Tatula SV TW 19 Tatula TW All Tatula models (SV/TW/CT/CT TYPE-R/HLC) /HD Custom/TW80) TD Zillion J Dream TD Zillion HLC/PE Fuego (Overseas Model) All PX68 models Gekka Bijin AIR TW PE SPECIAL Ryoga SSS 17 Fuego CT HRF PE Special etc. * The above is for reference only, please confirm size compatibility at your own risk. They rotate most smoothly when dry, but when installed in the spool system of a bait reel, a high-pitched "shhh" sliding noise may occur during casting. If this bothers you, apply a small amount of oil. (It should quiet down a bit.) * However, because they are full ceramic (PTFE for the ball retainer), they should not seize up like metal cage & metal ball bearings, even in the spool rotation range of a bait reel (even when dry). In other words, they won't rust (even in saltwater) and are (currently) ideal maintenance-free bearings that don't require oiling, etc. (Especially recommended for "Tatula series" reels, which do not require a shaft pin remover for replacement. 14 and 24 Tatula models are easy to replace because both are clip-fixed.) Non-magnetic material, so installation near the brake magnet is easy. Please note that after installing them in a reel, you may not be able to receive manufacturer warranty, so please do so at your own risk.