I see on the market a slotted hockey puck, such as the one on the right in the picture below. This flat-bottom adapter is meant to fit between a hydraulic floor jack and a vehicle's pinch welds.

I'm not sure what the adapter on the left in the picture above is meant to do, but when I hoist the vehicle with an ordinary scissor jack such as the one pictured below,

I would like to insert a rubber adapter between metal and metal. That adapter must have a slot below running parallel to the slot above.

What is the correct (rubber) adapter to avoid jacking with metal on metal?

(And a secondary question while we're at it. What is the purpose of the adapter on the left in the first picture above, where the above/below slots are perpendicular to one another?)

I see on the market a slotted hockey puck, such as the one on the right in the picture below. This flat-bottom adapter is meant to fit between a hydraulic floor jack and a vehicle's pinch welds.

The adapter on the left in the picture above is meant for use with a jack stand. The bottom would line up with the cup on the jack stand, and the top would match the pinch weld.

When I hoist the vehicle with an ordinary scissor jack such as the one pictured below,

I would like to insert a rubber adapter between metal and metal. That adapter must have a slot below running parallel to the slot above.

What is the correct (rubber) adapter to avoid jacking with metal on metal?