What material is the 39-375 made of?

Thanks for reaching out to us. The snap-fit covers are constructed of plastic, but the full-flip handles are die cast metal. 

I hope this answers your question. Please reach out if you wanted to know anything else!

The 39-375 is a Truth hardware part used across many different window brands. We would need to see a photo of your operator with the window open so that the base and arms that move the sash are fully visible to confirm if the 39-375 would be compatible. Thank you. 

The 39-375 and 39-376 handle and cover kits are not brand specific but if the specifications match up to your original parts, they certainly could work on your Marvin window. 

See the dimensions from the 39-375 product page below. Thank you. 

Width measurement

View of the handle extended

Side view

The 39-376 handle is designed to attach to an 11/32" diameter operator spline. Just let us know if you have any other questions and thanks for posting!