This is a Tonga 1896 Block of 4 SG 368, the SURCHARGE 7 1/2d OVPT READING UP on Half Penny Blue.  

These have partial paper adherents, as well as the usual gum.  This is VERY RARE to see this stamp in multiples with gum, no less!

This stamp is valued at L1800 in the Stanley Gibbons Catalogue.  Truly a rare and valuable block!

This lot is over $100 USD so I will ship it using Priority Mail in the US, and Registered Mail overseas.  This is to ensure that it reaches you in a safe and timely manner, and it includes tracking!