This is the most common sized mechanical seal. Fits dozens of brands of pumps. USA made. Not cheap Chinese imports. This is a much higher quality seal than some of the cheaper ones you find online with cheap rubbers and poor carbon faces.
3/4" type 6 premium silicon carbide mechanical seal Silicon Carbide primary ring / Silicon Carbide seat seal surface with Viton elastomers and stainless steel hardware for superior longevity against abrasion, corrosion & chemicals, and dry running - far more resistant to corrosives in the water. Silicon Carbide seat section rubber OD 35.4mm, Spring loaded Silicon Carbide section ID 18.7mm (inner measurement of rubber seal) Silicon Carbide Seat, Silicon Carbide ring, Viton Elastomer, Stainless Steel hardware.
Suits Spaquip Maxiflow, Monster, Magnum, Filtermaster, Balboa Super WOW, Hurlcon, Astralpool, Hayward and plenty of others
OD of Ceramic Base: 35.4mm (including rubber)
ID of Spring Section: 18.7mm
Height: 34mm (overall)