While we're waiting for Mike's reply from Norm....the one I purchased is like the one that old servi (Pete) posted in another thread in "Other things Simplex. My understanding from Pete is that it's very similar to the Simplex tail light, but there is only one bulb and the glass is solid red rather than clear at the bottom as the Simplex lens would have. Both lights however, were manufactured by Zephyr and styling is identical. I purchased mine from a fellow member on my Antique and Collectable Bicycle website, but that was the only one that he had. Attached is a photo of the one that Pete offered to sell me, which is exactly like the one I purchased, and I believe Pete's is still for sale.