This is a Parker DeLuxe Challenger Standard size model 439 in Gray with chrome plated trim from 1936. Parker advertised the DeLuxe Challenger button filler as Duofold quality for the $5.00 set market. Sets included a bottle of Parker Quink ink. They came in Standard and Slender sizes at $3.50 with a matching pencil for $1.50. It's 5 inches long. Also available in Burgundy and Green with gold plated trim. The cap and barrel material reminds one of the Sheaffer Ebonized Pearl material with square inlays. The nib is not hallmarked and may be gold plated stainless steel.