Can digest both p-nitro-phenyl-alpha-D-mannoside and high mannose oligosaccharide (Man(8)-GlcNAc(2)). May be involved in sperm maturation. Has a possible role in specific sperm-egg interaction since sperm surface mannosidase acts like a receptor for mannose-containing oligosaccharides located on the zona pellucida. Hydrolysis of terminal, non-reducing alpha-D-mannose residues in alpha-D-mannosides. Binds 1 zinc ion per subunit. Optimum pH is 6.5. Found at the sperm surface as a 27 kDa fragment. Specific to the caput and corpus of the epididymis. Processed into a 27 kDa fragment localized on the equatorial segment and the apical rim of the head of mature sperm. Belongs to the glycosyl hydrolase 38 family.