1. Device for adjusting and checking reed relays having a sealed glass envelope, a pair of metallic lead-ins fused into the material of said envelope and extending into the latter, and a pair of switching tongues in said envelope and each having an end portion conductively connected with one of said lead-ins, said device comprising first means for locally heating said one end portion of one of said tongues from outside said sealed glass envelope so as to render it plastically deformable; and second means operatively associated with said first means for magnetically deflecting said one tongue from the exterior of said sealed glass envelope while said one end portion is in plastically deformable condition, whereby to effect permanent deformation of said one end portion.