It's a blower(supercharger) snout coupler. There are many different lengths of couplers, this one is a 5.15" coupler. The flange of the coupler bolts up to the input flange on the blower, with the neck of the coupler facing away from the blower. The blower snout is a housing with a shaft/pulley flange and a bearing. The snout shaft slides into the coupler and the snout housing bolts to the blower housing. This coupler is drilled with 2 different sized holes, so (6)5/16" or (6)3/8" bolts can attach it to the blower input flange. The second link has an expolded view and part #1 is the coupler. Lots of companies make blower parts.

you need to include in your information how many teeth are on the internal spline, how many bolt holes are in the opposite end (flange end), diameter of each hole and the bolt circle diameter.

Reason:
I would like to know what this is specifically, what it goes to, what it does, what it's used for and who manufactures it. Thanks.

It's a blower(supercharger) snout coupler. There are many different lengths of couplers, this one is a 5.15" coupler. The flange of the coupler bolts up to the input flange on the blower, with the neck of the coupler facing away from the blower. The blower snout is a housing with a shaft/pulley flange and a bearing. The snout shaft slides into the coupler and the snout housing bolts to the blower housing. This coupler is drilled with 2 different sized holes, so (6)5/16" or (6)3/8" bolts can attach it to the blower input flange. The second link has an expolded view and part #1 is the coupler. Lots of companies make blower parts.

References:

https://theblowershop.com/shop/parts/drive-accessories/snouts-shafts-couplers...

https://theblowershop.com/wp-content/uploads/2022/02/SNOUT-INST-Sheet1.pdf