F0451A and F0491A spring return or not

There is nothing in the data sheets to say whether either of these two solenoids use an internal spring or require an external spring to be fitted or gravity to return to their extended non powered state. Does anyone know the answer?
Digikey part numbers 527-1016-ND and 527-1032-ND.
Thanks in advance.

In the absence of specification to the contrary, one can assume that such devices require an external force to return to an extended state.

Internal return springs subtract from the amount of pull force available, and applications calling for a pull-type actuator generally imply the presence of something to pull against.

So, using the same assumption, the fact digikey hasn’t got a sort filter for spring return means that digikey isn’t able to supply anything of the sort as well? I really hate assuming things…

On the off chance that someone actually has come across something suitable I should have mentioned in my original query that I was looking for a continuous rated, less than 2 amp draw, pull type action solenoid with 20mm or better stroke…the force required is low as it acts as a pin preventing a light weight object from passing… the engineer doesn’t want additional levers or external springs so I’m a bit stuck…

Any help appreciated.

If my Samsung Galaxy smartphone is so smart, why does it need me to help it do things?

Perhaps I should clarify; integral spring returns aren’t standard equipment on pull-type solenoids because they subtract from the intended function (pulling) and the character of the product as something that pulls implies that there is something to pull against, making spring return functions unnecessary for the hypothetical generic use case. It isn’t that such things don’t exist, but rather that it’s not a typical feature and therefore usually not present if unmentioned anywhere in the product literature.

Lack of a parametric filter for spring return functions implies only that the creation of one has not been found sufficiently needful to date.

If the ask is for a (12V?) continuous-duty pull-type solenoid drawing <2A with a stroke >=20mm and integral spring return, I find no item in our catalog at present matching this description. These would be the closest. If one’s willing to buy in quantity, an integral spring as a factory option may be available as a custom item.