BEWARE of eBay Seller coregaming! (https://www.ebay.com/fdbk/feedback_profile/coregaming!) and store CoreGMG (https://www.ebay.com/str/coregmg)!
They use a misleading term usage "Authentic" in the title for their Vectrex Vectrex Overlay sales.
In addition to the misleading listing title keyword, the seller's Vectrex overlays have following issues.
Low quality printing.
Flimsy plastic.
Does not include an opaque white layer on the back of the Overlay. Degrades appearance during game play.
Additionally, the seller produces fake overlays that never existed also listing them as "Authentic". Example, their "Vectrex Overlay - Authentic - 3D Crazy Coaster" overlay being sold at $59.99.(https://www.ebay.com/itm/285665237566). GCE / MB never made a Vectrex Overlay for any of their 3D Imager games.
Instead, buy an original era GCE / MB Vectrex overlay.
Or buy one of the other excellent reproduction overlays.
Either can be found for around $12.00 to $20.00.