This is a Gateway Wire brand part, #GW-TOISCWv2. This is not a Toto OEM part. Compare to Toto THU651N top mounting seat hardware for a compatible high-quality replacement bolt set. This part is intended for use with recessed toilet seat mounting holes that have no through-hole access.
Part Specifications:
Country of origin: China
Material: Rubber, nickel chrome, stainless steel
Length, bolt: 2.813in
Length, gasket: 2.375in
Width, washer: 0.709in
Width, gasket flange: 0.829in
Width, gasket sphere: 0.646in
Width, gasket shaft: 0.507in
Instructions for use:

Disassemble the two (2) included toggle bolt assemblies.
Insert each rubber gasket into the toilet seat mounting holes of a compatible toilet. Gaskets are fully inserted when the wide-lip flange on the top of the gasket rests flush against the base toilet fixture.
Place a compatible toilet seat on top of the toilet.
Position the seat hinge mounting holes over top of the bolt holes of the newly-installed gaskets. Some seats may require the removal of hinge covers to access the hinge mounting holes.
Place each washer over the toilet seat hinge mounting holes, and insert the compression bolts into the washer-hinge-gasket bolt holes.
Thread the bolts into the gasket bushings, starting by hand to prevent misalignment and crossthreading of the fasteners.
Doublecheck toilet seat placement and alignment with the base toilet fixture. Make any necessary adjustments.
Finish tightening the bolts by hand using a #2 Phillips-head screwdriver. Caution: the use of power tools is not advised, and may cause overtightening, injury or damage to the fixture.
If toilet seat hinge covers were removed for installation, reinstall the covers.