This is a Genuine OE Boss 4000 PSI Crossover Relief Valve HYD07027. Used on Boss RT3 Straight Blades with Smart Hitch 1 & 2. 

Used on the RED Valve Block (SH1) HYD07045 & (SH2) HYD07091. 

Used on the GREEN Valve Block (SH2) HYD07090

Used on the (SH2) with Serial # 400000000 & Higher with and without D-Force Valve Block HYD10171 & HYD07048. 

Alternate Part Numbers: HYD07027, 1-HYD7027