You are looking at an original 17th century pamphlet - some sime later bound / repaired - as described 

Heads of Agreement
assented to by the United Church in and about London
formerly called Presbyterian and Congreational 
London Printed by RR for Tho Cockerill at The Three Legs & John Dunton at The Raven 1691
title page [verso blank]
iv [4] pages prelims + 16 pages, 
measures 155mm x 200mm

Apparently scarce in current commerce [none offered for sale online] with only microfilm copies on Worldcat

Thank you for looking - increasingly uncommon thus
any questions please ask before bidding
sold with flaws described / shown