Temperature limiter for some Parmco ovens. Rated 65 degrees, this is the device that switches the cooling fan. 
Temperature Limiters Explained
PARMCO: OV-1-6S-5, OV-1-6S-8, OV-1-6W-5, OV-1-6W-8, OV-M1-6S-9, OV-M2-6S-9, OV-2-6S-5, OV-2-6S-8, OV-3-6S-5, OV-3-6S-8, OV-4-6S-5, OV-4-6S-8, OV-4-6W-8, OV-7, OV7-1-5, OV7-1-8,  OV7-1-6S-5, OV7-1-6S-8, OV7-3-8, OV7-1-6W-5, OV7-1-6W-8, OV7-2-6S-5,  OV7-3-6S-5, OV7-3-6S-8, OV-HIOV-1-GAS, OVHI6WFF, OVHI6SFF, OV-HI
PPOV-6S-DT-1, PPOV-6S-DT-2, PPOV-6S-DT-3, PPOV-6S-SIDE, PPOV-6S-PYRO, PPOV-6S-PYRO2 (only units prior to November 2017), PPOV-6S-10, PPOV-70, PPOV-9S-48, PPOV-6S-MULTI, PPOV-6S-MULTI-1, PPOV-6S-70, FS600BC FS600BG FS600SC FS600SG FS600SI FS60WC8 FS60WR4 FS60WR8 FS900BG FS900SC FS900SG OV145B7 OX7-4-6B-8-1 OX7-6-6S-5-1 OX7-3-6S-5-1 OX7-2-6S-5-1 PPOV-6S-SIDE-1 OX7-3-6S-8-1 OX7-2-6S-8-1 OX7-6-6S-8-1 PPOV-6S-DT-4 OX7-4-6W-5-1 OX7-4-6W-8-1 PPOV-6S-DT-3 FS600WG VS60WR4
EUROTECH: ED-EUROC90BK, ED-EUROC90SS, ED-BIO5FMTBK, ED-BIO5FMTBK.2, ED-BIO5FMTSS, ED-BIO8FDTBK, ED-BIO8FDTSS, ED-BIO11FTBK, ED-BIO11FTSS, ED-BIO11FTBK.2, ED-BIO11FTSS.2
EUROMAID: BG8SS-5 BM90S EO605DTB EO605MTS EO610ATB EO910TS EO916ASTB EPO617ASTB EPO917ASTB HNTB65XL
HAIER: 
TECHNIKA: TGO610FTSHL TO106MDST-R TO106MDSTL-5 TO106MDSTR-3 HE65FLSS TO106MDSTR-5 T45COG, TB60FSS-2 TB60FSS-3 TB62FLSS TB62FLSS-2 TB62FLSS-3 TB62FRSS TB62FRSS-3 TB65FLSS TB65FRSS TB86MSS TGO65D-2 TGO68TSHL TO106MDST TO106MDST-L TO106MDSTL-3 TO107SS TO56FSS TO56FSS-2 TO66PSS TO86MSS, T948SS-6 TGO610TBK TGO910FTBS TGO910TBK TGPO610FTSHL TTDT910-6 TO6005MX TO6006ATX TO6010ATB TO9010ASTB TO9010TB TPO6017APB, T640TE8 T640TE8LPG TEG64UA